Lines and Angles
Angle is the amount of turn between two straight lines that have a common end point (the vertex). A line is a collection of points along a straight path that goes on and on in opposite directions. A line has no endpoints.Watch Lines Angles Videos to learn more.
A true line in geometry is a straight bar that keeps going and going in both directions. We label lines by labeling any two points on the line and call the line by those two points.
(a) Segment:- – A part of line with two end points is called a line-segment.
(b) Ray:- – A part of a line with one end-point is called a ray.
(c) Collinear points: – If three or more points lie on the same line, then they are called collinear points, otherwise they are called non-collinear points.
(d) Angle:- An angle is formed by two rays originating from the same end point.
The rays making an angle are called the arms and the end-points are called the vertex.
Types of Angles:–
(i) Acute angle: -whose measure lies between 0° and 90°.
(ii) Right angle: -whose measure is equal to 90°.
(iii) Obtuse angle: – whose measure lies between 90° and 180°.
(iv) Straight angle: – The measure of a straight angle is 180°.
(v) Reflex angle: – which is greater than 180° and less than 360°.
(vi) Complimentary angle: – whose sum is 90°.
(vii) Supplementary angle: – Two angles whose sum is 180º.
(viii) Adjacent angle: – Two angles are adjacent, if they have a common vertex, common arm and their non-common arms are on different sides of the common arm.
(ix) Linear pair of angles: – If the sum of two adjacent angles is 180º, then their non-common lines are in the same straight line and two adjacent angles form a linear pair of angles.
Lines Angles Videos
Useful for CBSE, ICSE, NCERT & International Students
Grade : 9
Subject : Maths
Lesson : Lines and Angles
Topic: Lines Angles Videos
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