A scalene triangle has 3 sides of different lengths and 3 unequal angles. An isosceles triangle has 2 sides of equal length. (The dashes on the lines show which are equal in length.) The angles at the ...

Everyone learns the number one rule about triangles in high school: the angles of a triangle add up to 180 degrees. But did you know that sometimes they don't? Triangles are much more interesting than ...

A rectangle has two pairs of equal sides. It has four right angles (90°). The opposite sides are parallel. The diagonals bisect each other. A parallelogram has two pairs of equal sides. It has two ...