• # question_answer In the figure, AB and CD are common tangents to two circles of unequal radii. Prove that AB = CD.

 Construction: Extend AB and CD to meet at a point P Now, PA and PC are tangents of circle with centre O So                    $PA=PC$                                             ...(i) PB and PD are tangent on circle with centre O? So                    $PB=PD$                                             ...(ii) On subtracting eq. (ii) from eq. (i) $PA-PR=PCPD$ $AB=CD$                                Hence Proved