If cot-1 x + cot-1 y + cot-1 then x + y + z is equal to
If a, b, c be positive real numbers and the value of then tanθ is equal to -
=> θ = tan-1 0
=> tan θ = 0
The value of tan–1(1) + cos–1(–1/2) + sin–1(–1/2) is equal to -
Since, here we are considering only principle solutions
tan-1(1) = π/4
cos-1(-1/2) = 2π/3
sin-1(-1/2) = -π/6
Sol : π/4 +2π/3 -π/6
: 3π/4
L.H.S. and R.H.S. of the given equation are defined if
Value of
The Greatest value among tan1, tan-11, sin1, sin-11, cos1
Greatest value sin-11 = π/2
Where a and b are in their lowest form, then (a + b) equal to
On solving, we get
If domain of function f:x→x² + 1 is {0,1}, then its range is
The sum of the series cot–12 + cot–18 + cot–118 + cot–132 + ….. is
From the given equation
[we take only the +ve sign before the square root since
If tan (x + y) = 33 and x = tan–1 3, then y will be
tan (X + Y) = 33 --- eqn1
X = tan–1 3
So,
tan X = 3
eqn1 ⇒ 33 = (tanX + tanY)/(i-tanX*tanY)
33 = ( 3 + tanY )/( 1 – 3*tanY)
33 – 99*tanY = 3 + tanY
30 = 100 * tanY
tanY = 0.3
So, Y = tan-1(0.3)
The number of solutions of the equation belonging to the interval ( 0,1) is
⇒ x = 1(not possible)
The value of
If cos-1 x - cos-1 y/2 = α, then 4x2 − 4xy cos α + y2 is equal to
If [sin-1 cos-1 sin-1 tan-1x] = 1, ëû where [.] denotes the greatest integer function, then x belongs to the interval.
[x] = K, K ∈ Z ⇒ K < x < K + 1, where [x] represents integer part of x.
The value of sin-1 [cos(cos-1(cosx) + sin-1 (sinx))], where
sin-1 [cos(cos-1(cosx) + sin-1 (sinx))], where x€(π/2,π)
=> sin-1[cos(x + π-x)]
=> sin-1[cos(π)]
=> sin-1[-1]
=> -π/2
The principal value of
If x1, x2 , x3 , x4 are roots of the equation x4 - x3 sin 2β + x2 cos2β - x cosβ - sinβ Tan-1 (x1) + Tan-1 (x2) + Tan-1 (x3) + Tan-1(x4) can be equal to
The number of solutions of
Correct Answer :- D
Explanation : sin(2cos-1(cot(2tan-1x)))=0
2cos-1(cot(2tan-1x))=sin-10=0
cos-1(cot(2tan-1x))=0
cot(2tan-1x)=cos0
cot(2tan-1x)=1
cot(tan-1(2x/(1−x2)))=1
(1−x2)/2x=1
1−x2=2x
x2+2x−1=0
x=[−2±√(4+4)]/2
x=−1±√2, +-1
If xy + yz + zx = 1, then, tan–1x + tan–1y + tan–1z =
If xy + yz + zx = 1,
Then, 1 – xy – yz – zx = 0 ----- eqn1
tan-1x + tan-1y = tan-1((x+y)/(1-xy))
tan-1x + tan-1y + tan-1z = tan-1((x+y)/(1-xy)) + tan-1z
= tan-1( ( ((x+y)/(1-xy)) + z ) / (1 – ((x+y)*z)/(1+xy)))
= tan-1((x+y+z-xyz)/(1-xy-yz-zx))
= tan-1((x+y+z-xyz)/0) [From eqn1]
= π/2
then the value of tan-1 (sin A) + tan-1(sin3 A) + tan-1 (cot A cos A)
The equation
Cancelling x both sides (One root x=0)
25 = 3*(25-16x2)1/2 + 4*(25-9x2)1/2
25 - 3*(25-16x2)1/2 = 4*(25-9x2)1/2
Squaring both sides,
625 + 9*(25-16x2) – 2*25*3*(25-16x2)1/2 = 16*(25-9x2)
625 + 225 – 144x2 – 2*25*3*(25-16x2)1/2 = 400 – 144x2
450 = 2*25*3*(25-16x2)1/2
3 = (25-16x2)1/2
Squaring both sides
9 = 25 – 16x2
x2 = 1
x = ±1
So, roots of the equation are
x = -1, 0, 1
Sum of the roots is zero.
The number of real solution of
From function it is clear that
(1) x(x + 1) > 0 ∴ Domain of square root function.
(2) x2 + x + 1>0 ∴ Domain of square root function.
Domain of sin-1 function. From (2) and (3)
If 0 < x < 1, the numberof solutions of the equation tan-1(x-1) + tan-1 x + tan-1 (x+1) = tan-1 3x is
The given equation can be written as
tan-1(x-1) + tan-1 (x +1) = tan-1 3x - tan-1 x
If x2 + y2 + z2 = r2, then
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