CinderellaThe software for all this is available from Cinderella.
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Cinderella The software for all this is available from Cinderella. |
Java-based images
to use now on this page. (Return to main Cinderella page) |
| The angles in a triangle The diagram shows a yellow triangle, and three green copies of it. Use the orange vertices to move these green triangles so that the points A', B' and C' all coincide somewhere on the blue line. By using the yellow vertices to rotate the triangles, can you show that the three angles in any triangle add up to 180° ? |