What should be the angle between two vectors of magnitudes 3.20 and 5.70 units, so that their resultant has a magnitude of 6.10 units?

Question

Cos x = (b^2 + c^2 - a^2) / 2bc
Cos x = (3.2^2 + 5.7^2 - 6.1^2) / (2 * 3.2 * 5.7)
Cos x = 5.52/36.48
Cos x = 0.15
x = 81.3 degrees

Answer 1

Looks good to me.