Question

Given R vector = A vector+ B vector and R= A=B. The angle between A andB is...??​

Answer 1

Answer:

Angle is 120°

Explanation:

Using Pythagoras Theorem;

R=√(A^2 + B^2 + 2ABcos@)

As R=A=B therefore

A=√(A^2 + A^2 +2AAcos@)

A= √(2A^2 + 2A^2cos@)

Squaring on both sides;

A^2 = 2A^2 + 2A^2cos@

A^2 - 2A^2 = 2A^2cos@

-A^2 = 2A^2 cos@

-A^2/2A^2 = cos@

-1/2 = cos@

@ = cos^-1 (-1/2)

@ = 120°