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!
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Find, without the use of a calculator, the value of sinA, given that cos2A=5/13
Solution:
cos(2A)=1-2sin^(2A)
2sin^(2A)=1-cos(2A)
sin^(2A)=1/2(1-cos(2A)) =1/2(1-5/13)
sin(A)=2 square root 13/13