A triangle has sides A,B, and C. If the angle between sides A and B is (7pi)/12, the angle between sides B and C is pi/4, and the length of B is 7, what is the area of the triangle?

1 Answer
Jun 19, 2017

The area of the triangle is =33.5u^2

Explanation:

The angle between A and C is

=pi-(7/12pi+1/4pi)

=pi-10/12pi

=2/12pi=1/6pi

B=7

We apply the sine rule

A/sin(1/4pi)=B/sin(1/6pi)

A=(Bsin(1/4pi))/sin(1/6pi)

The area of the triangle is

=1/2*A*B*sin(7/12pi)

=1/2*B*(Bsin(1/4pi))/sin(1/6pi)*sin(7/12pi)

=1/2*B^2*(sin(1/4pi))/sin(1/6pi)*sin(7/12pi)

=1/2*49*1.366

=33.5