Question Details

Differentiate 2(tan⁡x)ᶜᵒᵗ⁡ˣ with respect to x

Options

A

2 csc²⁡x.tan⁡xᶜᵒᵗ⁡ˣ (1-log⁡(tan⁡x))

B

csc²⁡x.tan⁡xᶜᵒᵗ⁡ˣ (1-log⁡(tan⁡x))

C

2 csc²⁡x.tan⁡xᶜᵒᵗ⁡ˣ (1+log⁡(tan⁡x))

D

2tan⁡xᶜᵒᵗ⁡ˣ (1-log⁡(tan⁡x))

Correct Answer :

2 csc²⁡x.tan⁡xᶜᵒᵗ⁡ˣ (1-log⁡(tan⁡x))

Solution :

To differentiate y=2(tanx)cotx with respect to x, we state the correct option clearly:
The correct option is 2 csc²x.tanxᶜᵒᵗˣ (1-log(tanx)).

Let u=(tanx)cotx. The original function becomes y=2u, which gives:
d y d x = 2 d u d x

Taking the natural logarithm on both sides of the equation for u:
log u = log ( ( tan x ) cot x )

Using the power property of logarithms, we simplify the right-hand side:
log u = cot x · log ( tan x )

Differentiating both sides with respect to x using the product rule:
1 u d u d x = d d x ( cot x ) · log ( tan x ) + cot x · d d x [ log ( tan x ) ]

Recall the differentiation formulas:
ddx(cotx)=-csc2x
and by using the chain rule:
d d x [ log ( tan x ) ] = 1 tan x · sec 2 x = cos x sin x · 1 cos 2 x = 1 sin x cos x

Substitute these derivatives back:
1 u d u d x = - csc 2 x log ( tan x ) + cot x · 1 sin x cos x

Simplifying the second term:
cot x · 1 sin x cos x = cos x sin x · 1 sin x cos x = 1 sin 2 x = csc 2 x

Now we combine the terms:
1 u d u d x = - csc 2 x log ( tan x ) + csc 2 x

Factoring out csc2x:
1 u d u d x = csc 2 x ( 1 - log ( tan x ) )

Multiplying by u:
d u d x = u · csc 2 x ( 1 - log ( tan x ) )

Substitute u=(tanx)cotx back:
d u d x = ( tan x ) cot x csc 2 x ( 1 - log ( tan x ) )

Multiplying by 2 to get the final derivative of y:
d y d x = 2 csc 2 x · ( tan x ) cot x ( 1 - log ( tan x ) )

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