Question

Triangle ABC is such that AB = 8 cm, BC = 11 cm and AC = 15 cm. calculate correct to 2 decimal places the;

1. Angle ABC 
2. Radius of the circum circle 

Answer 1

1. 1. b² = a² + c² - 2acCos B
   15² = 11² + 8² - 2(11 x 8)Cos B
   225 = 185 - 176 Cos B
   176 Cos B = - 40
   Cos B = - 0.2273
   B = 103.14º 
2. ¹⁵/_{sin 103.14º}  = 2r
   R = 7.70cm