How does the tangram puzzle work?
You get the seven classic tangram pieces and a coloured shape to fill. Use all seven, with no overlaps and nothing sticking out. Drag a piece to move it, tap it to turn it a quarter turn, and use Flip to turn the parallelogram over. Pieces snap into place when you let go, and the puzzle is solved the moment they cover the shape exactly.
There are 12 shapes: square, triangle, rectangle, parallelogram, house, right trapezoid, tall trapezoid, slanted trapezoid, pentagon, shield, hexagon, long hexagon. Pick one or let the game choose. The clock starts on your first move.
How is your Tangram Puzzle time calculated?
Your result is your time from first move to the finished shape, with the number of moves (every drag, turn and flip) and hints beside it. Hint puts one piece in a right place and is counted. There is no rating: shapes differ a lot in difficulty, and no published average exists for them.
What are the seven tangram pieces?
Two large triangles, one medium triangle, two small triangles, a square and a parallelogram, all cut from one square. The square, the parallelogram and the medium triangle have the same area, each a large triangle is twice that, and each small triangle half of it.
| Piece | How many | Share of the whole square |
|---|---|---|
| Large triangle | 2 | 1/4 |
| Medium triangle | 1 | 1/8 |
| Small triangle | 2 | 1/16 |
| Square | 1 | 1/8 |
| Parallelogram | 1 | 1/8 |
Worked out from the pieces as the game draws them, which together cover the whole square exactly.
How do you solve a tangram?
Place the two large triangles first: together they cover half the shape, and only a few places fit them. Then the medium triangle, the square and the parallelogram, leaving the small triangles for the last corners. The parallelogram is the only piece that needs flipping; the others look the same mirrored.
- Look for right angles and long edges. A long straight edge of the shape is often the side of a large triangle.
- Fill corners first. A sharp, 45° corner can only take the point of a triangle or of the parallelogram.
- Use a hint when stuck. It places one piece for you and the rest often follows.
How many shapes can a tangram make?
Thousands of figures, but only thirteen convex ones, shapes with no dents. Fu Traing Wang and Chuan-Chih Hsiung proved that in 1942. This game uses 12 of the thirteen, each found by a search over the game's grid; the site's tests check that every one can be made.
The puzzle is thought to have been invented in China around the late 18th century, where it is called qīqiǎobǎn, “seven boards of skill”, and trading ships carried it to Europe and America soon after. The English word tangram first appears in print in 1848. For more shape puzzles, try Sliding Puzzle or the One Line Puzzle.