Question

PLEASE HELP

Which of the following graphs shows an angle that would have an equivalent cosine ratio to the graph shown?

Answer 1

Answer: 150 deg

Explanation:

cosine is negative in quadrants 2 and 3. the current angle, 210, is in quad 3. It will have an equal cosine value in quad 2.

that angle will be -210 degrees. in positive terms that is 360-210 = 150 degrees.

thus the answer which shows 150 degrees is correct.

in general:

`cos(x) = cos(-x)`