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Page 1 Integration Integrand and element of integration The function under the sign of integration is called integrand. For e.g. in 3 xdx ? ; x 3 is called integrand. In the integral f(x) dx ? , dx is known as the element of integration and it indicates the variable with respect to which the given function is to be integrated. Constant of integration : We know that 22 d (x ) 2x 2xdx x dx ?? ? Also 2 d (x c) 2x dx ?? ? 2 2xdx x c ? ? ? , where c is any constant So we notice that x 2 is an integral of 2x, then x 2 + c is also an integral of 2x. In general if f(x)dx ? = ?(x) then f(x)dx ? = ?(x) + c Standard formulae n1 n x xdx c n1 ? ?? ? ? , (n ? ?1) 1 22 1x sin c a ax ? ? ? ? ? 1 dx logx c x ?? ? 1 22 dx x cos c a ax ? ??? ? ? xx edx e c ?? ? 1 22 dx 1 x tan c aa ax ? ? ? ? ? x x e a adx log a ? ? + c 1 22 dx 1 x cot c aa ax ? ? ? ? ? ? cosxdx sinx c ?? ? 1 22 dx 1 x sec c aa xx a ? ? ? ? ? cosecxcotxdx cosecx c ??? ? 1 22 dx 1 x cosec c aa xx a ? ? ? ? ? ? sinxdx cosx c ?? ? ? sinhxdx ? = cos h x + c Page 2 Integration Integrand and element of integration The function under the sign of integration is called integrand. For e.g. in 3 xdx ? ; x 3 is called integrand. In the integral f(x) dx ? , dx is known as the element of integration and it indicates the variable with respect to which the given function is to be integrated. Constant of integration : We know that 22 d (x ) 2x 2xdx x dx ?? ? Also 2 d (x c) 2x dx ?? ? 2 2xdx x c ? ? ? , where c is any constant So we notice that x 2 is an integral of 2x, then x 2 + c is also an integral of 2x. In general if f(x)dx ? = ?(x) then f(x)dx ? = ?(x) + c Standard formulae n1 n x xdx c n1 ? ?? ? ? , (n ? ?1) 1 22 1x sin c a ax ? ? ? ? ? 1 dx logx c x ?? ? 1 22 dx x cos c a ax ? ??? ? ? xx edx e c ?? ? 1 22 dx 1 x tan c aa ax ? ? ? ? ? x x e a adx log a ? ? + c 1 22 dx 1 x cot c aa ax ? ? ? ? ? ? cosxdx sinx c ?? ? 1 22 dx 1 x sec c aa xx a ? ? ? ? ? cosecxcotxdx cosecx c ??? ? 1 22 dx 1 x cosec c aa xx a ? ? ? ? ? ? sinxdx cosx c ?? ? ? sinhxdx ? = cos h x + c secx tanxdx secx c ?? ? coshxdx ? = sin h x + c 2 sec x dx tanx c ?? ? 2 dx x1 ? ? = sin h ?1 x + c 2 cosec xdx ? = ?cot x + c 2 dx x1 ? ? = cos h ?1 x + c cotxdx ? = log sin x + c 2 dx x1 ? ? = tan h ?1 x + c tanxdx ? = log sec x + c tanxdx ? = ? log (cos x) + c ? ? secxdx log(secx tanx) c ?? ? ? secxdx ? ? ? ?? x log tan c 42 ??? ? ? ?? ?? ?? ? ? cosec x dx log(cosecx cotx) c ?? ? ? ? ? ? cosec x dx ? ? x log tan 2 ?? ?? ?? + c Important Trigonometric Identities ? sin 2 A + cos 2 A =1 ? sin (A + B) = sin A cos B + cos A sin B ? cos (A + B) = cos A cos B ? sin A sin B ? tan (A + B) = tanA tanB 1 tanA tanB ? ? ? sin (A ? B) = sin A cos B ? cos A sin B ? cos (A ? B) = cos A cos B + sin A sin B ? tan (A ? B) = tanA tanB 1 tanA tanB ? ? ? sin 2 A ? sin 2 B = sin (A + B) sin (A ? B) ? cos 2 A ? sin 2 B = cos (A + B) cos (A ? B) ? 2 sin A cos B = sin (A + B) + sin (A ? B) ? 2 cos A sin B = sin (A + B) ? sin (A ? B) ? 2 cos A cos B = cos (A + B) + cos (A ? B) Page 3 Integration Integrand and element of integration The function under the sign of integration is called integrand. For e.g. in 3 xdx ? ; x 3 is called integrand. In the integral f(x) dx ? , dx is known as the element of integration and it indicates the variable with respect to which the given function is to be integrated. Constant of integration : We know that 22 d (x ) 2x 2xdx x dx ?? ? Also 2 d (x c) 2x dx ?? ? 2 2xdx x c ? ? ? , where c is any constant So we notice that x 2 is an integral of 2x, then x 2 + c is also an integral of 2x. In general if f(x)dx ? = ?(x) then f(x)dx ? = ?(x) + c Standard formulae n1 n x xdx c n1 ? ?? ? ? , (n ? ?1) 1 22 1x sin c a ax ? ? ? ? ? 1 dx logx c x ?? ? 1 22 dx x cos c a ax ? ??? ? ? xx edx e c ?? ? 1 22 dx 1 x tan c aa ax ? ? ? ? ? x x e a adx log a ? ? + c 1 22 dx 1 x cot c aa ax ? ? ? ? ? ? cosxdx sinx c ?? ? 1 22 dx 1 x sec c aa xx a ? ? ? ? ? cosecxcotxdx cosecx c ??? ? 1 22 dx 1 x cosec c aa xx a ? ? ? ? ? ? sinxdx cosx c ?? ? ? sinhxdx ? = cos h x + c secx tanxdx secx c ?? ? coshxdx ? = sin h x + c 2 sec x dx tanx c ?? ? 2 dx x1 ? ? = sin h ?1 x + c 2 cosec xdx ? = ?cot x + c 2 dx x1 ? ? = cos h ?1 x + c cotxdx ? = log sin x + c 2 dx x1 ? ? = tan h ?1 x + c tanxdx ? = log sec x + c tanxdx ? = ? log (cos x) + c ? ? secxdx log(secx tanx) c ?? ? ? secxdx ? ? ? ?? x log tan c 42 ??? ? ? ?? ?? ?? ? ? cosec x dx log(cosecx cotx) c ?? ? ? ? ? ? cosec x dx ? ? x log tan 2 ?? ?? ?? + c Important Trigonometric Identities ? sin 2 A + cos 2 A =1 ? sin (A + B) = sin A cos B + cos A sin B ? cos (A + B) = cos A cos B ? sin A sin B ? tan (A + B) = tanA tanB 1 tanA tanB ? ? ? sin (A ? B) = sin A cos B ? cos A sin B ? cos (A ? B) = cos A cos B + sin A sin B ? tan (A ? B) = tanA tanB 1 tanA tanB ? ? ? sin 2 A ? sin 2 B = sin (A + B) sin (A ? B) ? cos 2 A ? sin 2 B = cos (A + B) cos (A ? B) ? 2 sin A cos B = sin (A + B) + sin (A ? B) ? 2 cos A sin B = sin (A + B) ? sin (A ? B) ? 2 cos A cos B = cos (A + B) + cos (A ? B) ? 2 sin A sin B = cos (A ? B) ? cos (A + B) ? 2 sin CD 2 ? cos CD 2 ? = sin C + sin D ? 2 cos CD 2 ? sin CD 2 ? = sin C ? sin D ? 2 cos CD 2 ? cos CD 2 ? = cos C + cos D ? 2 sin CD 2 ? sin DC 2 ? = cos C ? cos D ? cos 2A = cos 2 A ? sin 2 A = 1 ? 2sin 2 A = 2 cos 2 A ? 1 = 2 2 1tan A 1tan A ? ? ? sin 2A = 2 sin A cos A = 2 2tanA 1tan A ? ? tan 2A = 2 2tanA 1tan A ? ? sin 3A = 3 sin A ? 4 sin 3 A ? cos 3A = 4 cos 3 A ? 3 cos A ? tan 3A = 3 2 3tanA 4tan A 13tan A ? ? Note : Integration of mn sin xcos xdx ? where m and n are positive integers (i) If m be odd and n be even, for integration put t = cos x (ii) If m be even and n be odd, for integration put t = sin x (iii) If m and n are odd, for integration put either t = cos x or sin x (iv) If m and n are even, for integration put either t = cos x or sin x Solved Example 17 : Evaluate 3 sin x dx ? Solution : sin 3x = 3 sin x ? 4 sin 3 x 4 sin 3 x = 3 sin x ? sin 3x ? 4 3 sin x dx ? = ?? ? (3sinx sin3x) dx ? ?? ?? 3sinxdx sin3xdx 3 1cos3x sin xdx 3cosx c 43 ?? ? ?? ? ?? ?? ? Page 4 Integration Integrand and element of integration The function under the sign of integration is called integrand. For e.g. in 3 xdx ? ; x 3 is called integrand. In the integral f(x) dx ? , dx is known as the element of integration and it indicates the variable with respect to which the given function is to be integrated. Constant of integration : We know that 22 d (x ) 2x 2xdx x dx ?? ? Also 2 d (x c) 2x dx ?? ? 2 2xdx x c ? ? ? , where c is any constant So we notice that x 2 is an integral of 2x, then x 2 + c is also an integral of 2x. In general if f(x)dx ? = ?(x) then f(x)dx ? = ?(x) + c Standard formulae n1 n x xdx c n1 ? ?? ? ? , (n ? ?1) 1 22 1x sin c a ax ? ? ? ? ? 1 dx logx c x ?? ? 1 22 dx x cos c a ax ? ??? ? ? xx edx e c ?? ? 1 22 dx 1 x tan c aa ax ? ? ? ? ? x x e a adx log a ? ? + c 1 22 dx 1 x cot c aa ax ? ? ? ? ? ? cosxdx sinx c ?? ? 1 22 dx 1 x sec c aa xx a ? ? ? ? ? cosecxcotxdx cosecx c ??? ? 1 22 dx 1 x cosec c aa xx a ? ? ? ? ? ? sinxdx cosx c ?? ? ? sinhxdx ? = cos h x + c secx tanxdx secx c ?? ? coshxdx ? = sin h x + c 2 sec x dx tanx c ?? ? 2 dx x1 ? ? = sin h ?1 x + c 2 cosec xdx ? = ?cot x + c 2 dx x1 ? ? = cos h ?1 x + c cotxdx ? = log sin x + c 2 dx x1 ? ? = tan h ?1 x + c tanxdx ? = log sec x + c tanxdx ? = ? log (cos x) + c ? ? secxdx log(secx tanx) c ?? ? ? secxdx ? ? ? ?? x log tan c 42 ??? ? ? ?? ?? ?? ? ? cosec x dx log(cosecx cotx) c ?? ? ? ? ? ? cosec x dx ? ? x log tan 2 ?? ?? ?? + c Important Trigonometric Identities ? sin 2 A + cos 2 A =1 ? sin (A + B) = sin A cos B + cos A sin B ? cos (A + B) = cos A cos B ? sin A sin B ? tan (A + B) = tanA tanB 1 tanA tanB ? ? ? sin (A ? B) = sin A cos B ? cos A sin B ? cos (A ? B) = cos A cos B + sin A sin B ? tan (A ? B) = tanA tanB 1 tanA tanB ? ? ? sin 2 A ? sin 2 B = sin (A + B) sin (A ? B) ? cos 2 A ? sin 2 B = cos (A + B) cos (A ? B) ? 2 sin A cos B = sin (A + B) + sin (A ? B) ? 2 cos A sin B = sin (A + B) ? sin (A ? B) ? 2 cos A cos B = cos (A + B) + cos (A ? B) ? 2 sin A sin B = cos (A ? B) ? cos (A + B) ? 2 sin CD 2 ? cos CD 2 ? = sin C + sin D ? 2 cos CD 2 ? sin CD 2 ? = sin C ? sin D ? 2 cos CD 2 ? cos CD 2 ? = cos C + cos D ? 2 sin CD 2 ? sin DC 2 ? = cos C ? cos D ? cos 2A = cos 2 A ? sin 2 A = 1 ? 2sin 2 A = 2 cos 2 A ? 1 = 2 2 1tan A 1tan A ? ? ? sin 2A = 2 sin A cos A = 2 2tanA 1tan A ? ? tan 2A = 2 2tanA 1tan A ? ? sin 3A = 3 sin A ? 4 sin 3 A ? cos 3A = 4 cos 3 A ? 3 cos A ? tan 3A = 3 2 3tanA 4tan A 13tan A ? ? Note : Integration of mn sin xcos xdx ? where m and n are positive integers (i) If m be odd and n be even, for integration put t = cos x (ii) If m be even and n be odd, for integration put t = sin x (iii) If m and n are odd, for integration put either t = cos x or sin x (iv) If m and n are even, for integration put either t = cos x or sin x Solved Example 17 : Evaluate 3 sin x dx ? Solution : sin 3x = 3 sin x ? 4 sin 3 x 4 sin 3 x = 3 sin x ? sin 3x ? 4 3 sin x dx ? = ?? ? (3sinx sin3x) dx ? ?? ?? 3sinxdx sin3xdx 3 1cos3x sin xdx 3cosx c 43 ?? ? ?? ? ?? ?? ? Solved Example 18 : Evaluate sin3x cos2x dx ? Solution : 1 sin3xcos2xdx (sin5x sinx)dx 2 ?? ?? = 11 cos5x cos x 10 2 ? ? Solved Example 19 : Evaluate sin2xsin3xdx ? Solution : ?? ? ? ? ?? 1 sin2x sin3x dx cos x cos5x dx 2 = 11 sinx sin5x 210 ? Solved Example 20 : Integrate 22 dx cos xsin x ? Solution : Now, ? ? 22 22 22 1cosxsinx cos x sin x cos x sin x ?? 22 11 sin x cos x = cosec 2 x + sec 2 x [ ?1 = sin 2 x + cos 2 x] ? 22 dx cos xsin x ? = 22 (cosec x sec x)dx ? ? = 22 cosec xdx sec xdx ? ?? = ? cot x + tan x + c Solved Example 21 : Evaluate 33 sin x cos xdx ? Solution : We have sin 3 x cos 3 x = (sin x cos x) 3 = 1 8 (2 sin x cos x) 3 = 1 8 sin 3 2x = 11 84 ? (3 sin 2x ? sin 6x) [ ? 4 sin 3 x = 3 sin x ? sin 3x] = 1 32 (3 sin 2x ? sin 6x) ? ? 33 sin x cos xdx ?? ? 1 (3sin2x sin6x)dx 32 = 31 sin2xdx sin6xdx 32 32 ? ?? = 3 cos2x 1 cos6x c 32 2 32 6 ?? ?? ?? ? ? ?? ?? ?? ?? Hence ? ? 33 sin x cos x dx ? ? ?? 31 cos2x cos6x c 64 192 Solved Example 22 : Evaluate 1 dx 1sinx ? ? Solution : 111sinx 1 sinx 1 sinx 1 sinx ? ?? ?? ? = ? ? 2 1sinx 1sin x Page 5 Integration Integrand and element of integration The function under the sign of integration is called integrand. For e.g. in 3 xdx ? ; x 3 is called integrand. In the integral f(x) dx ? , dx is known as the element of integration and it indicates the variable with respect to which the given function is to be integrated. Constant of integration : We know that 22 d (x ) 2x 2xdx x dx ?? ? Also 2 d (x c) 2x dx ?? ? 2 2xdx x c ? ? ? , where c is any constant So we notice that x 2 is an integral of 2x, then x 2 + c is also an integral of 2x. In general if f(x)dx ? = ?(x) then f(x)dx ? = ?(x) + c Standard formulae n1 n x xdx c n1 ? ?? ? ? , (n ? ?1) 1 22 1x sin c a ax ? ? ? ? ? 1 dx logx c x ?? ? 1 22 dx x cos c a ax ? ??? ? ? xx edx e c ?? ? 1 22 dx 1 x tan c aa ax ? ? ? ? ? x x e a adx log a ? ? + c 1 22 dx 1 x cot c aa ax ? ? ? ? ? ? cosxdx sinx c ?? ? 1 22 dx 1 x sec c aa xx a ? ? ? ? ? cosecxcotxdx cosecx c ??? ? 1 22 dx 1 x cosec c aa xx a ? ? ? ? ? ? sinxdx cosx c ?? ? ? sinhxdx ? = cos h x + c secx tanxdx secx c ?? ? coshxdx ? = sin h x + c 2 sec x dx tanx c ?? ? 2 dx x1 ? ? = sin h ?1 x + c 2 cosec xdx ? = ?cot x + c 2 dx x1 ? ? = cos h ?1 x + c cotxdx ? = log sin x + c 2 dx x1 ? ? = tan h ?1 x + c tanxdx ? = log sec x + c tanxdx ? = ? log (cos x) + c ? ? secxdx log(secx tanx) c ?? ? ? secxdx ? ? ? ?? x log tan c 42 ??? ? ? ?? ?? ?? ? ? cosec x dx log(cosecx cotx) c ?? ? ? ? ? ? cosec x dx ? ? x log tan 2 ?? ?? ?? + c Important Trigonometric Identities ? sin 2 A + cos 2 A =1 ? sin (A + B) = sin A cos B + cos A sin B ? cos (A + B) = cos A cos B ? sin A sin B ? tan (A + B) = tanA tanB 1 tanA tanB ? ? ? sin (A ? B) = sin A cos B ? cos A sin B ? cos (A ? B) = cos A cos B + sin A sin B ? tan (A ? B) = tanA tanB 1 tanA tanB ? ? ? sin 2 A ? sin 2 B = sin (A + B) sin (A ? B) ? cos 2 A ? sin 2 B = cos (A + B) cos (A ? B) ? 2 sin A cos B = sin (A + B) + sin (A ? B) ? 2 cos A sin B = sin (A + B) ? sin (A ? B) ? 2 cos A cos B = cos (A + B) + cos (A ? B) ? 2 sin A sin B = cos (A ? B) ? cos (A + B) ? 2 sin CD 2 ? cos CD 2 ? = sin C + sin D ? 2 cos CD 2 ? sin CD 2 ? = sin C ? sin D ? 2 cos CD 2 ? cos CD 2 ? = cos C + cos D ? 2 sin CD 2 ? sin DC 2 ? = cos C ? cos D ? cos 2A = cos 2 A ? sin 2 A = 1 ? 2sin 2 A = 2 cos 2 A ? 1 = 2 2 1tan A 1tan A ? ? ? sin 2A = 2 sin A cos A = 2 2tanA 1tan A ? ? tan 2A = 2 2tanA 1tan A ? ? sin 3A = 3 sin A ? 4 sin 3 A ? cos 3A = 4 cos 3 A ? 3 cos A ? tan 3A = 3 2 3tanA 4tan A 13tan A ? ? Note : Integration of mn sin xcos xdx ? where m and n are positive integers (i) If m be odd and n be even, for integration put t = cos x (ii) If m be even and n be odd, for integration put t = sin x (iii) If m and n are odd, for integration put either t = cos x or sin x (iv) If m and n are even, for integration put either t = cos x or sin x Solved Example 17 : Evaluate 3 sin x dx ? Solution : sin 3x = 3 sin x ? 4 sin 3 x 4 sin 3 x = 3 sin x ? sin 3x ? 4 3 sin x dx ? = ?? ? (3sinx sin3x) dx ? ?? ?? 3sinxdx sin3xdx 3 1cos3x sin xdx 3cosx c 43 ?? ? ?? ? ?? ?? ? Solved Example 18 : Evaluate sin3x cos2x dx ? Solution : 1 sin3xcos2xdx (sin5x sinx)dx 2 ?? ?? = 11 cos5x cos x 10 2 ? ? Solved Example 19 : Evaluate sin2xsin3xdx ? Solution : ?? ? ? ? ?? 1 sin2x sin3x dx cos x cos5x dx 2 = 11 sinx sin5x 210 ? Solved Example 20 : Integrate 22 dx cos xsin x ? Solution : Now, ? ? 22 22 22 1cosxsinx cos x sin x cos x sin x ?? 22 11 sin x cos x = cosec 2 x + sec 2 x [ ?1 = sin 2 x + cos 2 x] ? 22 dx cos xsin x ? = 22 (cosec x sec x)dx ? ? = 22 cosec xdx sec xdx ? ?? = ? cot x + tan x + c Solved Example 21 : Evaluate 33 sin x cos xdx ? Solution : We have sin 3 x cos 3 x = (sin x cos x) 3 = 1 8 (2 sin x cos x) 3 = 1 8 sin 3 2x = 11 84 ? (3 sin 2x ? sin 6x) [ ? 4 sin 3 x = 3 sin x ? sin 3x] = 1 32 (3 sin 2x ? sin 6x) ? ? 33 sin x cos xdx ?? ? 1 (3sin2x sin6x)dx 32 = 31 sin2xdx sin6xdx 32 32 ? ?? = 3 cos2x 1 cos6x c 32 2 32 6 ?? ?? ?? ? ? ?? ?? ?? ?? Hence ? ? 33 sin x cos x dx ? ? ?? 31 cos2x cos6x c 64 192 Solved Example 22 : Evaluate 1 dx 1sinx ? ? Solution : 111sinx 1 sinx 1 sinx 1 sinx ? ?? ?? ? = ? ? 2 1sinx 1sin x ? ?? ? 22 2 1sinx 1 sinx cosx cosx cosx or 1 1sinx ? = sec 2 x ? tan x sec x ? ? ? 1 dx 1sinx ?? ? 2 (sec x tanxsec x)dx = ?? ? ?? 2 sec x dx tanx sec x dx ?? ? tanx sec x c Solved Example 23 : Evaluate 76 sin x cos xdx ? Solution : ? ? 76 sin x cos x dx ? ? 66 sin x cos x sinxdx = 23 6 (1 cos x) cos xsinxdx ? ? = ?? ? ? 24 6 (1 3cos x 3cos x cos x) 6 cos x sinxdx = ?? ? ? 68 10 12 (cos x 3cos x 3cos x cos x) sinxdx = 6 8 10 12 (t 3t 3t t )dt ?? ? ? ? by putting t = cos x = ? 7 9 11 13 tt t t 33 7 9 11 13 ?? ? = ? ?? 79 11 11 3 cos x cos x cos x 73 11 ? 13 1 cos x 13 Solved Example 24 : Evaluate 63 sin x cos xdx ? Solution : ?? ? ?? 63 6 2 sin x cos x dx sin x(1 sin x)cos xdx = 68 (sin x sin x)cos x dx ? ? = 68 (t t )dt ? ? ? by putting sin x = t = 79 11 tt 79 ? = 79 11 sin x sin x 79 ? Solved Example 25 : Evaluate 42 sin x cos xdx ? Solution : sin 4 x cos 2 x = 1 8 (2 sin 2 x) 2 (1+cos2x) = 1 8 (1 ?cos2x ? cos 2 2x + cos 3 2x) = 1 8 ? ? ?? ? ? 1cos4x 1cos2x 2 ? ? ? ? ? cos6x 3cos2x 4 = 1 8 11 1 1 cos2x cos4x cos6x 24 2 4 ?? ??? ?? ?? = 11 1 1cos2x cos4x cos6x 16 2 2 ?? ?? ? ?? ?? ? 42 sin x cos xdx = ?? ?? ? ?? ?? 11 1 1 cos2x cos4x cos6x dx 16 2 2 = 11 1 1 xsin2x sin4x sin6x 16 4 4 12 ?? ??? ?? ??Read More
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