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

Answer 1

draw your triangle. It is in QIV, where x is positive and y is negative.

Now, recall that
r^2 = x^2+y^2 and r is always positive
sinθ = y/r
cosθ = x/r

Now just read off the values from your triangle.