Solve the Triangle a140 ft b180 ft c210 ft What is the measu

Solve the Triangle.

a=14.0 ft.           b=18.0 ft.                c=21.0 ft.

What is the measure of angle A?

What is the measure of angle B?

What is the measure of angle C?

Solution

cos A= (b^2 + c^2 -a^2)/(2bc)

cos A= (18^2 + 21^2 -14^2)/(2*18*21)= (324+441-196)/756=569/756

A=cos^-1(566/756)=41.18 degree

Cos B= (a^2 + c^2 -b^2)/2ac

         = (196 + 441-324)/588=313/588

B=cos^-1(313/588)=57.84 degree

A=180-(B+C)=180-(41.18+57.84)=80.98 degree