A line is a superficial figure with no density and can be extended in both directions. Mostly, it is called straight line only to highlight that there are no arcs anywhere in it. In a figure, PQ and QR are two lines merging at a tip Q ; the tip Q is called as vertex. The gap between two lines highlighted as Q is called an angle. Line segment refers to the part of line which has two end points. Line segment PQ is indicated by PQ. Ray refers to a part of the line which a single end point in one side and an arrow in other side which indicates that it can be extended on one direction . If three or more than three points are on the same line, they are called collinear points, and if not, they are called non collinear points. The lines which bisect each other at a midpoint known as intersecting lines, and the lines which are parallel to each other known as non intersecting lines. The dimensions of the similar perpendicular at diverse tips on these parallel lines are similar. This similar dimension is called as the distance between two parallel lines.
Definition of an angle
An angle is an extent formed between two lines that merge at a tip and the meeting point called the vertex. The two lines deriving from the similar tip are called as the arms of the angle. The angles are divided into diverse categories such as Acute Angle, Right Angle, Obtuse Angle, Straight Angle , Reflex Angle and Full Angle. These angles are summarised below:-
a) Acute Angle refers to the angle which is more than 0 degree but below 90 degrees.
b) Right angle refers to the angle which is equal to 90 degrees
c) Obtuse angle refers to the angle which is more than 90 degrees but less than 180 degrees.
d) A straight angle refers to the angle which is equal to 180 degrees.
e) Reflex Angle refers to the angle which is more than 180 degrees but less than 360 degree.
f) Whole Angle refers to the angle which is equal to 360 degrees.
When a merge of the angles is made, they are named differently based on few rules. The identification of the angle merge and the rules are given below
1) Complementary angles:- Two angles whose sum is 90 degrees are called as complementary angles
2) Supplementary angles :- Two angles whose sum is 180 degrees are called supplementary angles
3) Adjacent angles:- Two angles are adjacent if they share a common vertex , similar arms and non similar arms are on opposite sides of the common arm.
4) Vertically opposite angles:- These angles are created when two lines bisect each other at a point.
5) Linear Pair Of Angles:- These angles are formed when the sum of the two adjacent angles is equal to 180 degrees.
6) Parallel Lines and transversal: A line that bisects two or more lines at different edges is called as transversal.
Angle Sum Property of a triangle
- The sum of the angles of triangle is 180 degrees . Angle A+ Angle B+ Angle C= 180 degrees
- If the side of triangle is created, then outer angle is created which is similar to the sum of two inner opposite angles. Angle D= Angle A+ Angle B
