Use the given information to find the exact value of the exp

Use the given information to find the exact value of the expression. sin theta = 4/5, theta lies in quadrant I Find cos 2 theta. 7/25 -7/25 -9/25 24/25

Solution

sin theta=4/5

opposite=4 , hypotenuse=5

adjacent=sqrt(25-16)=9

cos 2 theta= 1-2sin²theta =1-2(16/25)=1-32/25=-7/25