Definite-Integration Question 522

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

[EAMCET 1992]

Options:

A) $ \frac{2}{15} $

B) $ \frac{4}{15} $

C) $ \frac{6}{15} $

D) $ \frac{8}{15} $

Show Answer

Answer:

Correct Answer: B

Solution:

$ \int_{-\pi /2}^{\pi /2}{{{\sin }^{2}}x{{\cos }^{2}}x(\sin x+\cos x)dx} $ = $ \int_{-\pi /2}^{\pi /2}{{{\sin }^{3}}x{{\cos }^{2}}xdx+\int_{-\pi /2}^{\pi /2}{{{\sin }^{2}}x{{\cos }^{3}}x,dx}} $ $ =0+2\int_0^{\pi /2}{{{\sin }^{2}}x{{\cos }^{3}}xdx} $ $ =0+2\times \frac{2}{15}=\frac{4}{15} $ .