CEMC Fermat, 2001

Geometry Difficulty 2.0 Junior Find the answer Canada

In right triangle $ABC$ , $AX = AD$ and $CY = CD$ , as shown. The measure of $\angle XDY$ is

(A) $35^\circ$ (B) $40^\circ$ (C) $45^\circ$ (D) $50^\circ$ (E) not determined by this information

Figure for this problem

We don't reproduce this publisher's solutions. Their own solution is here — work the problem first.

Want a route through all this instead of an archive? The track puts 2,604 problems in a working order, from Junior Challenge level to the IMO shortlist.

Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project. Solutions are the publisher's, linked not copied.