Find the possible values of the included angle of a triangle with : sides 5cm and 8cm, and the area 15cm^2??

Find included angle of a triangle knowing: area = 15 cm^2, sides 5 cm and 8 cm.

Use the trig identity: S = 1/2 bc.sin A S --> Area = 15 ; side b = 5; side c = 8; find sin A ##sin A = (2S)/(bc) = (2(15))/(5(8)) = 30/40 = 3/4 = 0.75## Calculator --> ##A = 48.59## deg or ##A = 180 - 48.59 = 131.41## deg