What is the angle (in degree) between A vector and B vector . . .

Question : What is the angle (in degree) between A and B, if A and B are the adjacent sides of a parallelogram drawn from a common point and the area of the parallelogram is AB/2?

Doubt by Suhani 

Solution : 

Area of parallelogram whose adjacent sides are represented by A and B = |A×B|

AB/2 = |ABSinθ n cap|
AB/2 = ABSinθ | n cap| 
AB/2 = ABSinθ × 1 [∵ Magnitude of n cap is 1]
1/2 = sinθ
sin 30° = sinθ
θ = 30°

Hence, the angle between A and B is 30°