Question

SinΘ = 15/17 and Θ lies in Q1, find cos 2Θ

Answer 1

`\cos^2\theta=1-\sin^2\theta`

`\cos^2\theta=1-(225)/(289)=(64)/(289)`


`\cos2\theta=\cos^2\theta-\sin^2\theta`

`\cos2\theta=(64)/(289)-(225)/(289)=-(161)/(289)`