Question

if a line interest two concentric circle with centre of at a, b, c, d, prove that ab=cd​

Answer 1

Answer:

We know that, OA=OD and OB=OC.

They are radius of respective circles.

In ΔOBC, we know that OB=OC, so ∠OBC=∠OCB

∴∠OCD=∠OBA

In ΔOAD, we know that OA=OD, so ∠OAD=∠ODA

Since, ∠OCD=∠OBA and ∠OAD=∠ODA, we get ∠AOB in ΔOAB is equal to ∠COD in ΔOCD.

∴ From SAS congruency, we can say that ΔOAB and ΔOCD are congruent.

So, AB=CD.

Answer 2

Step-by-step explanation:

at first draw two concentric circle and then radii of a circle are equal.