In figure 3.79, O

(1)Given: OE AD, AB = 12, AC = 8

⇒ AD × AC = AB²

This property is known as tangent secant segments theorem.

⇒ AD × 8 = 12²

(2)DC = AD – AC = 18 – 8 = 10

(3)As we know that a perpendicular from centre divides the chord in two equal parts. Here, OE AD.

⇒ DE = EC

⇒ DE + EC = DC

⇒2DE = DC