The value of $\int\limits_{-\frac{\pi}{2}}^{\frac{\pi}{2}}(\sin|x|+\cos|x|) dx$ is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 4
Given integral:
$I = \int_{-\frac{\pi}{2}}^{\frac{\pi}{2}} \left( \sin|x| + \cos|x| \right) dx$
Since $\sin|x|$ is even and $\cos|x|$ is even, the integrand is even.
$I = 2 \int_{0}^{\frac{\pi}{2}} \left( \sin x + \cos x \right) dx$
Integrating:
$I = 2 \left[ -\cos x + \sin x \right]_{0}^{\frac{\pi}{2}}$
$I = 2 \left[ (-\cos \frac{\pi}{2} + \sin \frac{\pi}{2}) - (-\cos 0 + \sin 0) \right]$
$I = 2 \left[ (0 + 1) - (-1 + 0) \right]$
$I = 2 \left[ 1 + 1 \right]$
$I = 4$