Definition of a opposite rays  two rays with a common endpoint that form a straight line .
Math Open Reference

Definition and properties of isosceles triangles
Math Open Reference

Included side definition: The common leg of two angles.
Math Open Reference

Hypotenuse definition: The longest side of a right triangle.
Math Open Reference

A method for calculating the area of a triangle when you know all three sides.
Math Open Reference

Definition and properties of equilateral triangles
Math Open Reference

Definition of equidistant point  a point the same distance from two or more other points
Math Open Reference

Definition and properties of equiangular triangles
Math Open Reference

Definition and properties of the diameter of a circle
Math Open Reference

Formula and description of the volume of a cube.
Math Open Reference
