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Draw out a copy of the diagram, and it will help if you draw on the triangle DAC.

Mark on any angles that you can calculate.

There are various ways you can show that two triangles are congruent, which are sometimes called RHS, SSS, SAS, ASA.  Since you know more angles than sides, the ASA condition is probably most helpful.

Two triangles are similar if they have the same set of angles.  Similar triangles are enlargements of each other.