Find rightarrow A middot rightarrow B and the angle between

Find rightarrow A middot rightarrow B and the angle between rightarrow A and rightarrow B where rightarrow A = (5, -3) and rightarrow B = (2, 7)

Vector A= (5,-3) and Vector B= (2,7)

Vector A . Vector B= I A I I B I cos theta

Vector A . Vector B= 5*(2) + (-3)(7)=-11

I A I= sqrt(5²+ (-3)²) = sqrt(34)

I B I = sqrt(2² + 7²) = sqrt 53

-11= sqrt34 * sqrt 53 cos theta

cos theta=-11/(sqrt(34*53))

theta=cos^-1(-11/sqrt(34*53)) = 105degree