Simple Similar Triangles

Drag points A, B, and C to change the size and shape of the blue triangle, and its white counterpart that is similar (constrained by proportional SAS). Drag the Red point D to change the ratio in sizes. Observe the multitude of calculated output lengths and angles, and how they match the proportion value, proving similarity, regardless of the triangles' shapes/sizes.

Tags: Triangles, Similar, Ratios, Draggable, Outputs,

Pedal Triangles

The loci of the midpoints of the sides of pedal triangles form ellipses as the pedal point moves around a circle.    

Tags:

Similar Triangle Incenter

This problem showed up in a math competition. See what you can make of it.  

Tags: incenter, circle, similar-triangles

Triangle Areas

Can you triangles with integer side lengths and integer area?

Tags: triangle, area