A painter is going to apply a special coating to a triangula

A painter is going to apply a special coating to a triangular metal plate on a new building. Two sides measure 13 cm and 19.7 cm. She knows that the angle between the two sides is 108degree. What is the area of the surface she plans to cover with the coating? The surface area is cm^2.

Solution

Surface Area = (1/2) ab sin c

= (1/2) 13 *19.7* sin (108)

= (1/2) 13*19.7*0.951

= 121.78 cm²

^{or you can solve by below method as well}

Two sides are 13cm and 19.7cm. Let third side be c.

c²=a² + b² - 2ab cos (c)

c²= 169 + 388.09 -2*13*19.7*(-0.309)

c = 23.602