Similar triangles · समरूप त्रिभुज
Same shape, different size — use the ratio to find the missing side.
Similar triangles games
Similar triangles समरूप त्रिभुज
Two triangles are similar (△ABC ~ △PQR) when their corresponding angles are equal and their corresponding sides are in the same ratio — same shape, any size.
| Criterion | What you need |
|---|---|
| AAA (or AA) | angles equal (two are enough) |
| SSS | all three sides in the same ratio |
| SAS | one angle equal, the two sides around it in the same ratio |
Basic proportionality theorem (Thales)
If DE ∥ BC, then AD/DB = AE/EC. The converse is also true: if the sides are cut in the same ratio, DE is parallel to BC.
Areas: for similar triangles, ratio of areas = (ratio of sides)². Shadows: a pole and a tower with their shadows at the same time make similar triangles. Also see congruence of triangles, Pythagoras theorem and heights and distances.
Goes with NCERT Mathematics Class 10, Chapter Triangles. Answers worked out exactly.
A one-page chart to stick on the wall, and a worksheet to practise.
Similar triangles
Similar triangles समरूप त्रिभुज
Two triangles are similar (△ABC ~ △PQR) when their corresponding angles are equal and their corresponding sides are in the same ratio — same shape, any size.
| Criterion | What you need |
|---|---|
| AAA (or AA) | angles equal (two are enough) |
| SSS | all three sides in the same ratio |
| SAS | one angle equal, the two sides around it in the same ratio |
Basic proportionality theorem (Thales)
If DE ∥ BC, then AD/DB = AE/EC. The converse is also true: if the sides are cut in the same ratio, DE is parallel to BC.
kheloaurseekho.in — free charts, games and worksheets
Similar triangles — worksheet
Name: ____________________ Class: ______ Date: __________
kheloaurseekho.in — free charts, games and worksheets