Question

Express each of the following in terms of a reference angle. Explain, please.

1a. sin 45º 1b. 135º 1c. sin 225º 1d. sin 315º

3a. cos 224.5º 3b. cos 658º 3c. 145.7º 3d. sin (-201º)

Answer 1

Let A be the angle, R be reference angle

Quad 1: R =A
Quad 2: R = 180-A
Quad 3: R = A-180
Quad 4: R = 360 -A

Answer 2

if angle greater than 360, subtract 360 first

if angle is neg, add 360 first

Answer 3

i don't understand....

Answer 4

what do you mean?

sin(135) = sin(45) because 135 degrees is in 2nd Quadrant, 180-135 = 45