1. ## Solving trigonmetric equations

For $\displaystyle \frac{\pi}{2}<x<\pi$ with $\displaystyle \cos x = -\sin \frac{\pi}{6}$, find the value of x.

The question also states to not evualate the value of $\displaystyle \sin \frac{\pi}{6}$

How do I do this question?

2. Originally Posted by user_5
For $\displaystyle \frac{\pi}{2}<x<\pi$ with $\displaystyle \cos x = -\sin \frac{\pi}{6}$, find the value of x.

The question also states to not evualate the value of $\displaystyle \sin \frac{\pi}{6}$

How do I do this question?
Dear user_5,

Use the trignometric identity, $\displaystyle cos\left(\frac{\pi}{2}+A\right)=-sinA$