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Question
From an external point P, two tangents, PA and PB are drawn to a circle with centre O. At one point E on the circle tangent is drawn which intersects PA and PB at C and D, respectively. If PA = 10 cm, find the the perimeter of the triangle PCD.
Solution
Two tangents PA and PB are drawn to a circle with centre O from an external point P
Perimeter of ΔPCD = PC + CD + PD
= PC + CE + ED + PD
= PC + CA + DB + PD
= PA + PB
= 2PA
= 2(10)
= 20 cm ...[∵ CE = CA, DE = DB, PA = PB tangents from internal point to a circle are equal]
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