Why triangles are strong
Connect triangle rigidity with bridges, roofs and frames.
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Connect triangle rigidity with bridges, roofs and frames.
Explain congruence as exact matching in shape and size.
Pair vertices, sides and angles correctly in congruent triangles.
Use vertex order to show correct correspondence.
Prove triangles congruent using two sides and the included angle.
Prove triangles congruent using three pairs of equal sides.
Prove triangles congruent using two angles and included side.
Prove triangles congruent using two angles and a non-included side.
Prove right triangles congruent using hypotenuse and one side.
Use examples to show ambiguity in side-side-angle data.
Recognise special conditions where side-side-angle information is enough.
Use congruence reasoning to establish equal base angles.
Show that equal angles in a triangle imply equal opposite sides.
Draw conclusions about equal sides or angles after congruence is established.
Break a statement into condition and result.
Reverse condition and conclusion and judge the meaning.
Show that a statement is false by giving one valid exception.
Use given information and theorems rather than visual appearance alone.
Use congruence criteria to solve geometric and real-world problems.
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