Triangle -- from Wolfram MathWorld

A triangle is a 3-sided polygon sometimes (but not very commonly) called the trigon. Every triangle has three sides and three angles, some of which may be the same. The sides of a triangle are given special names in the case of a right triangle, with the side opposite the right angle being termed the hypotenuse and the other two sides being known as the legs. All triangles are convex and bicentric. That portion of the plane enclosed by the triangle is called the triangle interior, while the

Outer Napoleon Triangle -- from Wolfram MathWorld

Spherical Coordinates -- from Wolfram MathWorld

Wolfram Math World: Law of Sines Handout for 9th - 10th Grade

Using Wolfram, Alpha to Understand Mathematics

Leibniz Harmonic Triangle -- from Wolfram MathWorld

Extangents Triangle -- from Wolfram MathWorld

Triangle Dissection Paradox -- from Wolfram MathWorld

Rhombic Hexecontahedron -- from Wolfram MathWorld

Second Morley Triangle -- from Wolfram MathWorld