Question

The vectors a and b have the same magnitude. The angle between the vectors is 125°, and the magnitude of their cross product is 20. What is |vector a|?

Answer 1

cross product = |a| * |b| * sin(theta)

since both vectors have the same magnitude

cross product = |a| * |a| * sin(theta)

plug in theta, the cross product, and solve for |a|