I can't understand the question

1) If a line intersects to concentric circle with centre O at A, B, C, and D. prove that AB = CD.

Dear Student,



$$\begin{gathered} Given: Two concentric circles with centre O, line l intersects the two circles at A, B, C, and D \\ To prove: AB = CD \\ Construction: Drop a perpendicular from O to line l intersecting it at M. \\ Proof: OM \perp BC [By construction] \\ \Rightarrow BM = MC [Perpendicular from centre of a circle to a chord bisects the chord] ...\left(i\right) \\ OM \perp AD [By construction] \\ \Rightarrow AM = MD [Perpendicular from centre of a circle to a chord bisects the chord] ...\left(ii\right) \\ \therefore AM - BM = MD - MC [From \left(i\right) and \left(ii\right)] \\ \Rightarrow AB = CD \\ Hence, proved \end{gathered}$$

Hope this information will clear your doubts about the topic.

​If you have any more doubts, please ask here on the forum and our experts will help you out as soon as possible.

​Regards