Circles

• Angle in a semi circle is a right angle.

Example: 

Find the value of ∠PQR in the given figure.

Solution:

In ΔPQR, ∠PQR + ∠QRP + ∠RPQ = 180°

⇒∠PQR + 90° + 32° = 180°

⇒∠PQR = 180° − 90° − 32° = 58°

• The angle subtended by an arc at the centre of the circle is double the angle subtended by the arc at the remaining part of …