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 they are equal in length. The angles at the ...

Polygons can be regular or irregular. If the angles are all equal and all the sides are equal length it is a regular polygon. To find the sum of interior angles in a polygon divide the polygon into ...

Named for Plato, who theorized that the classical elements were made of these regular polyhedrons, three of the Platonic solids are composed of equilateral triangles: the tetrahedron, octahedron, and ...

vi) (Motivate) If a side of a triangle is produced, the exterior angle so formed is equal to the sum of the two remote interior angles. 2. Triangles i) (Motivate) Two triangles are congruent if any ...