The Lengths of Two Vectors a and B, and the Angle

Essay

The lengths of two vectors a and b, and the angle $\theta$ between them, are given. Find the length of their cross product, $| \mathbf { a } \times \mathbf { b } |$ . $| \mathbf { a } | = 4 , |\mathbf { b }| = 5 , \theta = 60 ^ { \circ }$