The amount of space measured in degrees. The vertex is the point where the two straight lines come together to form the angle. Notice that the angle symbol is in the shape of a box. That symbol indicates that you are dealing with a right angle. A central angle is an angle of which the vertex is located in the center of a circle.
Adjacent angles are angles that have the same vertex and one side in common.
Opposite angles are formed by two straight lines crossing and are always equal. It may help to understand why this is so. When two straight lines cross, four angles are created. Most plants and factories are said to be built along the major lines of the compass. Fractions of the Ruler Much of our work is lined up to be level or plumb .