If the bisectors of the base angles of a triangle enclose an angle of 135°, prove that the triangle is a right triangle.
Given bisector og the base angles of a triangle enclose an angle of 135o
i.e. ∠BOC = 135o
But,
135o = 90o + ∠A
∠A = 135o – 90o
∠A = 45o (2)
= 90o
Therefore, is right angled triangle right angled at A.