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Starting a congruence or similarity proof
As an initial strategy, add any information contained in the text of the problem to the diagram.
Then identify the different triangles by highlighting them in different colours. Redraw the triangles at the side of the main diagram if visualisation is difficult. The naming of corresponding vertices, angles and sides in the two triangles is critical.
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List the four tests. Then systematically eliminate the inappropriate tests by looking for:
 a right angle
 side relationships
 angle relationships.
Once the correct test has been selected, write a structured proof.

Introduce the two triangles.
In subsequent lines, information relating to the first triangle should be written first.

State the facts in the order required by the test.
This alerts students to look for the matching side or the included angle and also clearly supports the test.

Conclude with a statement of congruence or similarity, writing the vertices in matching order.
This is a requirement of the congruence (\(\cong\)) and similarity (\(\sim\)) symbols. It also helps in the subsequent matching of sides, angles or proportions
The facts which were previously unknown are now confirmed true and can be used to prove further results.