Two circles intersect at two points $ B $ and $ C $. Through $ \mathrm{B} $, two line segments $ \mathrm{ABD} $ and $ \mathrm{PBQ} $ are drawn to intersect the circles at $ A, D $ and $ P $, $ Q $ respectively (see in figure below). Prove that $ \angle \mathrm{ACP}=\angle \mathrm{QCD} $. "
Given:
Two circles intersect at two points \( B \) and \( C \). Through \( \mathrm{B} \), two line segments \( \mathrm{ABD} \) and \( \mathrm{PBQ} \) are drawn to intersect the circles at \( A, D \) and \( P \), \( Q \) respectively.
To do:
We have to prove that \( \angle \mathrm{ACP}=\angle \mathrm{QCD} \).
Solution:
We know that,
Angles in the same segment are equal.
In the larger circle,
$\angle ACP =\angle ABP$...…(i) (Angles in the same segment)
In the smaller circle,
$\angle QCD = \angle QBD$...…(ii) {Angles in the same segment)
$\angle ABP = \angle QBD$...…(iii) (Vertically opposite angles)
From (i), (ii) and (iii), we get,
$\angle ACP = \angle QCD$.
Hence proved.
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