Triangles

Two figures are similar when corresponding angles are equal and corresponding sides are in the same ratio. This idea extends far beyond triangles, but triangles give the cleanest theorems and proofs.

When triangles are similar, a wide set of side ratios and area relations become available. These results are essential in geometry proofs and measurement problems.

The standard criteria are AA, SSS and SAS. Students should not just memorise these names, but understand what information each criterion requires and why it works.

In many Class 10 syllabi, triangles also connect to Pythagoras theorem and its converse. This builds a bridge between similarity ideas and right-triangle measurement.

The main outcome is the ability to prove similarity, set up correct ratios, compare areas and use triangle theorems in exam-style questions.