A point on the terminal side of angle #\theta# is (9, 12). What is cos #\theta#?

1 Answer
Dec 5, 2017

cos t = 3/5

Explanation:

#tan t = y/x = 12/9 = 4/3#
Use trig identity
#cos^2 t = 1/(1 + tan^2 t)#
In this case:
#cos^2 t = 1/(1 + 16/9) = 9/25#
#cos t = +- 3/5#
Since t is in Quadrant 1, then, cos t is positive
#cos t = 3/5#