Find the required expression without using a calculator :
1. sin2A, give sinA=3/5
2. cos2A, given cosA=3/5
3. tan2A, given tanA=1/2
Now my problem is use the trigo identities to find sin2A. cos2A and tan2A. i know can use triangle to find, but problem is not allow use triangle to find exact value.
THX who Helping!