What is #cos theta# if #(12, -5)# is a point on the terminal side of #theta#?

1 Answer
Apr 18, 2017

#cos(theta) = 12/13#

Explanation:

The terminal arm should form the hypotenuse side of a right triangle such that #12^2 + (-5)^2 = c^2 = 169;# that is #c=13 # , the hypotenuse side. #a=12#, the adjacent side, and #b=-5# , the opposite side.
#cos (theta) = (adjacent)/(hypoten\use) = 12/13#