Answer:

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:

