Question

The point (3, -4) is on the terminal side of an angle . What is cos ?

Answer 1

Cos angle = adj/hyp
3 is the adj, -4 is the opposite, so use Pythagorean theorem to find the hypotenuse.
3^2 + (-4)^2 = c^2
9 + 16 = c^2
25 = c^2
5 = hyp
Cos angle = 3/5
To find angle use cos^-1
Cos^-1 (3/5) = angle
Angle =
53.1 degrees