In the adjoining figure, O is the centre of the circle and P, Q and R are points on the circle such that ∠PQR = 100°, then ∠OPR equals:

• 80°   

• 10°

• 100° 
• 100° 

A and B are points on the circle with centre
O. If a chord CD of the circle subtends an angle of 50° at the point A on the circle and ∠BDC = 70°, then ∠BCD equals:

• 60°
• 50°
• 70°
• 70°

In the given figure, ∠AOB = 90° and ∠ABC = 30°, then ∠CAB is equal to:

• 30°  
• 105°
• 90°
• 90°

• 15 cm
• 6 cm
• 5 cm
• 5 cm

In the circle with centre O, ∠AOB = 60° and ∠BOC = 30°, the measure of ∠ADC is:

• 30°
• 45°
• 60°
• 60°