Question

The figure given below, shows a Circle with centre O.
Given: ∠AOC = a and ∠ABC = b.

Find the relationship between a and b

Answer 1

∠ ABC = `1/2` Reflex (COA)

(Angle at the centre is double the angle at the circumference subtended by the same chord)

⇒ b = `1/2 (360 - "a")` 

⇒ a + 2b = 360°