Question

Find the value of sin2A,cos2A when cosA =3/5

Answer 1

Cos a=3/5

Sin a= [1-(3/5)^2]^1/2

Sin a= 4/5 and -4/5

Sin2a=2 sina cosa

=2×4/5×3/5

=24/25

Cos 2a=cos^2 a- sin^2 a

=9/25-16/25

=-7/25

Hope it helps u

@skb