Derivative of cos with respect to x is
Differentiate with respect to x.
(cosx − sinx)/(cosx + sinx) = (1 − tanx)/(1 + tanx)
tan(A − B) = (tanA − tanB)/(1 + tanAtanB)
= tan(π/4−x)
putting this value in question.
tan−1 tan(π/4−x)
π/4 − x.
so d(π/4 − x)/dx = -1
The dervative id sec-1 x is
y = sec−1 x
by rewriting in terms of secant,
⇒ secy = x
by differentiating with respect to x,
⇒ secy tany y'= 1 by dividing by secy tany,
⇒ y'= 1/secy tany
since secy = x and tanx = √sec2y − 1 = √x2−1
⇒ y'= 1/x√x2−1
Hence, d/dx(sec−1x) = 1/x√x2−1
If y + sin y = 5x, then the value of dy/dx is
y + sin y = 5x
dy/dx + cos ydy/dx = 5
dy/dx = 5/(1+cos y)
Derivative of tan-1 x is
If xy = 2, then dy/dx is
xy = 2
x dy/dx + y = 0
x dy/dx = -y
dy/dx = -y/x
If 3 sin(xy) + 4 cos (xy) = 5, then = .....
3sinxy + 4cosxy = 5
⇒ 5(3/5 sinxy + 4/5 cosxy) = 5
⇒ (3/5 sinxy + 4/5 cosxy) = 1
now (3/5)²+(4/5)² = 1
so let, 3/5 = cosA
⇒ 4/5 = sinA
So , (3/5 sinxy + 4/5 cosxy) = 1
⇒ (cosAsinxy + sinAcosxy) = 1
⇒ sin(A+xy) = 1
⇒ A + xy = 2πk + π/2 (k is any integer)
⇒ sin⁻¹(4/5) + xy = 2πk + π/2
differenciating both sides with respect to x
0 + xdy/dx + y = 0
dy/dx = -y/x
y = tan-1(1-cosx)/sinx
y = tan-1{2sin2(x/2)/(2sin(x/2)cos(x/2)}
y = tan-1{tan x/2}
y = x/2 => dy/dx = 1/2
cos-1[(1-x2)/(1+x2)]
Put x = tanθ
y = cos-1(1 - tan2θ)/(1 + tan2θ)
y = cos-1(cos2θ)
y = 2θ……………….(1)
Put θ = tan-1 x in eq(1)
y = 2(tan-1 x)
dy/dx = 2(1/(1+x2))
dy/dx = 2/(1+x2)
now differentiate y with respect to x,
dy/dx = -{[x d/dx(1+x) - (1+x)dx/dx]}/(1+x2)
= -1/(1+x)2
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