### Home > PC3 > Chapter 11 > Lesson 11.2.5 > Problem11-147

11-147.

Given $\cos(A) = \frac { 5 } { 13 }$ where $0 < A <\frac { \pi } { 2 }$, evaluate $\csc(A)$ and $\cos(2A)$.

Sketch a right triangle for the given situation and then determine the length of the missing leg.

$\csc(A) = \frac{1}{\sin(A)}$

$\cos(2A) = \cos^2 (A)- \sin^2(A)$