Question

please solve it u have to just prove given above​

Answer 1

Key Point:-

Vectors A.B = |A|×|B|×cos@

where, A and B are vectors, |A| and |B| are its magnitude and @ is the angle between vectors A and B.

Answer:-

as, vectors R = A-B

squaring both sides, we get-

R^2 = (A-B)^2

or, R^2 = A^2+B^2-2(A.B)

or, R^2 = A^2+B^2-2×A×B×cos@

Hence, Proved...

Answer 2

Answer:

hope it helps you... ..