From an external point P, two tangents, PA and PB are drawn to a circle with centre 0. 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 perimeter of the triangle PCD.

Explanation

Two tangents PA and PB are drawn to a circle O from an external point P.

Perimeter of `DeltaPCD=PC+CD+PD`
`=PC+CE+ED+PD`
`PC+CA+DB+PD`
`=PA+PB`
`2PA=2(10)`
=20cm
[`:'CE=CA,DE=DB,PA=PB` tangents from internal point to a circle are equal]