Pedal tryangle

[BinduMathlover]

Kono trivuj er 2nd pedal triangle deoa thakle ki tar pedal point nirnoy kora jabe? Gele kivabe?

[Moon]

Try to use the cyclic quadrilaterals to prove that $\angle JIH=180^0-BDC$. So what you need to do it to erect triangles on the sides of the $\triangle ABC$ which has angle $JIH$ as the angle opposite to $D$. Then the circumcircles of these three triangles will intersect at the pedal point $D$.