Triangles
Drag the vertices of a triangle on a grid, measure its sides and angles, name its type, and explore constructions, triangle centres and area.
Free, runs in the browser, no sign-in or installation.
- Subject
- Mathematics
- Area
- Geometry
- Level
- Primary school
What you can do
- Drag the vertices on a 1 cm grid to see the side lengths and angles, and the triangle's type by sides and by angles.
- Tear off the angles to make a straight angle, and explore exterior angles, the triangle inequality and area as half a parallelogram.
- Follow SSS, SAS, ASA and SSA constructions with compasses step by step, and show altitudes, medians, perpendicular and angle bisectors, circumcircle and incircle.
- Practise with checked answers: sort triangles in a game of 10, decide whether a triangle can be drawn, and work out angles, perimeter and area.
- Print a worksheet for each topic or 1 cm grid paper, and save the drawing as a PNG.
Pictures in the Gallery13
Ready-made pictures made in this app, to download as PNG.
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