IMC Key Stage 3 · 6. Angles, triangles and congruence
Chase angles with angle sums, exterior angles and isosceles triangles; compare lengths with congruent triangles, bisectors and parallels; add an extra point when the data run out.
IMC Key Stage 3 – Selected topics
Use the angle sum, exterior angles and parallel lines to find unknown angles.
Turn equal sides into equal angles and solve chains of isosceles triangles with one variable.
Prove lengths equal with valid congruence cases, midpoints, bisectors and parallels.
Add a well-chosen extra point and recognise the meeting point of bisectors.