find the angle between vector U=<2,3> and V=<1,-5> answers: 88 degrees, 45 degrees, 135 degrees, or 92 degrees...?

Answer 1

U∘V = |U| |V|cos Ø, where Ø is the angle between
2 - 15 = √13√26cosØ
cosØ = -13/13√2
= -1/√2
Ø = 135°

Answer 2

A point on the terminal side of an angle theta is given. Find the exact value of the six trigonometric functions of theta:
(2,-3)