Question

Three vectors A,B and C are such that A=B+C and their magnitudes are 5,4 and 3 respectively.find the angle between A and C​

Answer 1

B = A - C

=> B² = A² + C² - 2AC.cos(A,C)

=>

`cos(a.c) = \frac{a {}^(2) + c {}^(2) - b {}^(2) }{2ac} = \frac{5 {}^(2) +3 {}^(2) - 4 {}^(2) }{2.5.3} = (3)/(5)`

=> angle between A and C = 53.13⁰