In the given figure, BOC is a diameter of a circle and AB = AC. Then, ABC = ?

Given: BOC is the diameter of the circle


AB = AC


Here, BAC forms a semicircle.


We know that angle in a semicircle is always 90


BAC = 90


Here ABC = ACB (since angles opposite equal sides are equal in a triangle)


We know that sum of all the angles in the triangle is 180


That is


ABC + ACB + BAC = 180


2 × ABC + BAC = 180


2 × ABC + 90 = 180


2 × ABC = 180 – 90


2 ×ABC = 90


ABC = 45

3