Evaluate $\int_{0}^{\frac{\pi}{2}}$ $cos2x$ $dx$

The correct answer is $0$

$\int_{0}^{\frac{\pi}{2}}$ $cos2x$ $dx$


= $ \left[ \dfrac{1}{2} sin2x \right]_0^{\frac{\pi}{2}} $


= $ \dfrac{1}{2} \left[ sin2 (\dfrac{\pi}{2}) - sin2 (0) \right]$


= $ \dfrac{1}{2} \left[ 0 - 0 \right]$


= $0$