Step-by-step explanation:
The Law of Sines
It is an equation relating the lengths of the sides of a triangle to the sines of its opposite angles. If A, B, and C are the lengths of the sides and a,b,c are their respective opposite angles, then:
We have completed the figure with the variable x for angle BDA. Thus
Solving for x:
Calculating:
Since angles ADC and x are linear, their sum is 180° and: