Prove that tangents drawn at the ends of a diameter of a circle are parallel.
To prove
Given Diameter = PQ
Centre = O
Proof
Theorem Tangent drawn at any point of the circle is perpendicular to the radius through the point of contact.
Now, (According to the above theorem)
Similarly, (According to the above theoram)
From eq (i) and (ii)
and
Therefore,
Or
For lines AB and CD and transversal PQ
(Both alternate angles are equal)
Hence lines are parallel