Question

The figure shows two circles which intersect at A and B. The centre of the smaller circle is O and lies on the circumference of the larger circle. Given that ∠APB = a°.

Calculate, in terms of a°, the value of : obtuse ∠AOB,

Give reasons for your answers clearly.

Answer 1

 
Obtuse ∠AOB = 2∠APB = 2a° 

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