3 7 2 16 Use an addition or subtraction formula to write the expression as a trigonometric function of one number and then find its exact value cos 10 cos 80 sin 10 sin 80 4 7 3 9 Find tan 2x given 1 tan x cos x 0 5 7 3 Use the appropriate half angle formula to find the exact value of the expression after first converting from radians to degrees Show ALL work TL sin sin 0