Let the intersections of and be and . Point is on arc of and is on arc on . and meet at and ; and meet at and . If and meet at and and meet at , then prove: .
Solution
Let the intersections of and be and . Point is on arc of and is on arc on . and meet at and ; and meet at and . If and meet at and and meet at , then we need to prove that .
First, note that from angle chasing, we have:
which implies that is a cyclic quadrilateral. Similarly, we can show that , , and are all cyclic quadrilaterals.
Next, observe that:
which implies that . Similarly, we have .
Additionally, note that:
and:
leading to . This similarity implies:
By similar means, we have:
Therefore, we obtain:
Since is a parallelogram, we have . Thus, we conclude that:
The answer is: .
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