6. Trigonometric Identities and More Equations

Use the given information to find each of the following.

sin x, given cos 2x = 2/3 , with π < x < 3π/2

Simplify each expression.

√[(1 + cos 76°)/2]

Given $\tan\theta=\frac{5}{12}$ and 0 < $\theta$ < $\frac{\pi}{2}$, find $\cos\left(2\theta\right)$.