Given pi SolutionTheta is in third quadrant cos theta817 adj

Solution

Theta is in third quadrant

cos theta=-8/17

adjacent=8

hypotenuse=17

opposite=15

sin theta=opposite/hypotenuse=-15/17

sin 2theta=2sintheta cos theta=2(-8/17)(-15/17)=240/289

cos 2 theta= cos^2 theta -sin^2 theta =(-8/17)^2 -(-15/17)^2

=64/289-225/289 =-161/289