The larger of two complementary angles is 60 larger than the others why is measurement of the larger of the two angles

A=Point (5,7) when represented in terms of vector = 5 i + 7 j

B=Point (-8,2) ,when represented in terms of vector = -8 i + 2 j

Dot Product of two vectors = A.B

Keep in mind

1.⇒i.i=1, j.j=1,i.j=j.i=0

2.Dot product of two vectors is Scalar Quantity.

So,→ A. B= (5 i + 7 j) . (-8 i +2 j)

       = 5 × -8 +7 × 2

         = -40 +14

        = -26