### Home > PC > Chapter 6 > Lesson 6.1.2 > Problem6-30

6-30.

If $\sin θ = \frac { 2 } { 3 }$ and $\frac { \pi } { 2 } ≤ θ ≤ π$, find $\cos θ$. You will need a unit circle diagram or a sketch of the graph of $y = \sin x$, in addition to the Fundamental Pythagorean Identity, to help you answer this.

Draw a triangle diagram and label known sides.

Determine the length of the missing side.

Evaluate cos(θ). What sign should be used?