Chapter 10 : Tangents to a circle

Example 1. In figure, chords AB and CD of the circle intersect at O. OA = 5cm, OB = 3cm and OC = 2.5cm. Find OD.

Solutions: - Chords AB and CD of the circle intersect at O

Example 2. In figure. Chords AB and CD intersect at P.

If AB = 5cm, PB = 3cm and PD = 4cm. Find the length of CD.

Solution:- PA = 5 + 3 = 8cm

PA X PB = PC X PD

Or, 8 X 3 = PC X 4

Or, PC = 8 X 3/4 = 6cm

CD = PC - PD

= 6 - 4

= 2cm