Find the Exact Value of the Given Trigonometric Function of the Angle

Multiple Choice

Find the exact value of the given trigonometric function of the angle $\theta$ shown in the figure. (Use the Pythagorean Theorem to find the third side of the triangle.) Find: $\cos \theta$

A) $\frac { 8 } { 17 }$
B) $\frac { 15 } { 17 }$
C) $\frac { 8 } { 15 }$
D) $\frac { 15 } { 8 }$
E) $\frac { 17 } { 15 }$