Question

Working with double and half angle identities. Picture attached below. Please show me how to solve this.

Answer 1

First, figure out what tan(A) would be based on your sin(A) value.
Then, use the tan(2A) formula here
http://www.sosmath.com/trig/douangl/douangl.html

Answer 2

sin(A) = 5/13
Find cos(A) using the identity: sin^2(A) + cos^2(A) = 1

tan(2A) = sin(2A) / cos(2A) = 2sin(A)cos(A) / { 1 - 2sin^2(A) }

Answer 3

Ok so how do i find cos(A) using that identity?

Answer 4

You can simply use the Pythagorean ratios to get the cos(A) from the givens