Question
Thu February 26, 2009 By:

Circles

Expert Reply
Fri February 27, 2009

OP2= PT2+ r2     (By pythagora's theorem)

PT2 = OP2-r2

OP2= OD2 + PD2

       = r2- x2 + (PA + x)2

PT2 = r2- x2 + (PA + x)2-r2

        = PA2 +2PA.x

        = PA (PA + 2x)

2x = AB

PT2 = PA. (PA+AB)

       = PA.PB

Hence Proved.

Home Work Help