Let ABCD be a parallelogram such that AB = 10, BC = 14, and angle A = 45 degrees. Find the area of the parallelogram.

A formula for the area of a parallelogram is:  Area  =  a · b · sin(C)

For it to apply in this situation, we need the size of angle B:  angle(B)  =  180^o - angle(A)  =  135^o.

Area  =  10 · 14 · sin(135^o)  =  ...

in this case ONLY...   area = 10*14/sqrt(2)