If theta = 3pie/4 find the exact value of each expression below.

Question

a) cos2theta

b) cos^2theta

c) cos(-theta)

Answer 1

a) cos2theta

b) cos^2theta

c) cos(-theta)

As Theta = 3pi/4

Cos2theta = Cos 3pi/2 = 0

Cs^2 Theta = Cos^2 3pi/4 =(-1/√2)^2 = 1/2

Cos ( -Theta ) = Cos theta = Cos 3pi/4 = -1/√2