An angle is formed when two lines intersect each other. An angle involves two legs and one common vertex at which two lines meet. For example, Angle AOD is formed when line AB and CD intersect with each other. Linear Pair of Angles: When the sum of two adjacent angles is 180 degree, then they are called a linear pair of angles. (i) If a ray stands on a line, then the sum of two adjacent angles so formed is 180 degree. (ii) If the sum of two adjacent angles is 180 degree, then a ray stands on a line (that is the non-common arms form a line).
"Construction" in Geometry means to draw shapes, angles or lines accurately. These constructions use the only compass, straightedge (i.e. ruler) and a pencil. It is the "pure" form of geometric construction: no numbers involved! Construction of Angles equal to a given angle. Draw an angle of measure 700. Please make a copy of it using ruler and compasses. Chapter 14 deals with basic terms, types of lines, types of angles and the construction of angles.