Question

(Q) In the figure O is the centre of the circle. angle BAC=40degree and angle BCO=30degree (a) What is the measure of angle ABC (b)Find the measure of angle AOC​

Answer 1

Answer:

Angle ABC=70°

Angle AOC=140°

Step-by-step explanation:

In △ABO, AO=BO⇒∠BAO=∠ABO=30°

In △CBO, CO=BO,⇒∠BCO=∠CBO=40°

⇒∠ABC=∠ABO+∠CBO=30+40=70°

Angle subtended at the center is twice the angle subtended anywhere on the arc, so,

Angle subtended at the center is twice the angle subtended anywhere on the arc, so,∠AOC=2×∠ABC=140°