Question

The figure shows two chords drawn on either sides of a diameter. How much is the angle the other chord makes with the diameter?

Answer 1

AD is the diameter and O is the centre of the circle.

∠OAB = 40°

Consider ΔOAB and ΔOAC

AB = AC = 3cm

OC = OB (Radius of the circle)

OA = OA (Common side)

Three sides ΔOAB of are equal to three sides of ΔOAC

In equal triangles, angle opposite to equal sides are equal.

∴ ∠OAB = ∠OAC

∴ ∠OAC = 40°