Question

11. In the given figure, BO and CO are the bisectors
of /_B and /_C respectively. If /_A = 50° then
BOC = ?
(a) 130°
(b) 100°
(c) 115°
(d) 120°
​

Answer 1

let the angles if the triangle be a,b,c

then a+b+c=180

b+c=180-50

b+c=130

dividing by two on both sides

b/2+c/2=65

in triangle BOC

b/2+c/2+o=180

65+o=180

o=115

if you do not remember this much simply remember this formula

o=90+(a/2)