Definite Integration Question 95

Question: $ \int_0^{\pi /2}{{}}(\sin x-\cos x)\log (\sin x+\cos x)dx= $

[SCRA 1986]

Options:

A) $ -1 $

B) 1

C) 0

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

Put $ \sin x+\cos x=t\Rightarrow -(\sin x-\cos x)dx=dt $

Also as $ x=0 $ to $ \frac{\pi }{2},t=1 $ to 1.

Since here limit is -1 to 1-, therefore the value of integral will be zero, $ { \because \int_a^{a}{f(x)dx=0} } $ .