3 Find the exact value of the expression below Show your wor

3.) Find the exact value of the expression below. (Show your work).

Solution

cos160 cos40 + sin 160 sin 40 = cos 160 cos(-40) - sin160 sin(-40)

=cos(160 - 40) = cos 120 = -1/2

2.

cos2x = 1/2

2x = 60 or 2x= 360-60

so x =30 or x = 150

x = pi/6 or x = 5*pi/6

3

sin^(-1) (sqrt(2)/2) = sin^(-1) (1/sqrt(2) ) =pi/4