Here is a quick way to review Lines and Angels. With this Quick Review, you can learn quickly Important Definitions, Important Facts, Important Formulae, and Important Procedures of chapter Lines and Angels. If you have doubts, you can post it to our 24 x 7 x 365 discussion forum and let one of the experts help you.

1. MB0906: Lines and Angels
Quick Review
 1350+ Videos;
 Well-detailed solutions to 3500+ problems
 Practice assignments
Get FREE Help in Maths at www.mathbuster.in
 HOTS quizzes
 Self-assessment quizzes
 Model Test Papers
 Expert guidance by mathematicians
Buy Your Online Subscription Today (Starting at Rs. 199 per month) and Enjoy:
24 x 7 x 365 Access
to high quality content to learn, practice and assess.
24 x 7 x 365 Question & Answer Forum
to get the best help for your doubts and difficulties.
Learn math anywhere, anytime with
students from across India and abroad.
© 2013 – 2018, ECPL, New Delhi. This document is part of the MathBuster online education program. All intellectual rights associated to this document directly or indirectly are
owned by ECPL and any reproduction, derivation or distribution of this document in original or modified in full or parts, either in manual or electronic form is prohibited unless a
written approval is obtained. This document has been downloaded from www.mathbuster.in for personal and non-commercial use. For any queries, contact math@elipsis.in
1
Thank you!
We appreciate your visiting MathBuster and downloading this study document.
If you have any doubts or difficulties, send your queries to mathbusterforum@googlegroups.com
Important Definitions
1. Part of a line with two end points is called a line segment while the part of the line with one end
point is called a ray.
2. If three or more points lie on a same line then they are called collinear points; otherwise they are
called non-collinear points.
3. The rays making an angle are called the arms of the angle, while the end point is called the vertex of
the angle.
4. An angle measuring between 0 and 90 is called an acute angle.
5. An angle measuring 90 is called a right angle.
6. An angle measuring between 90 and 180 is called an obtuse angle.
7. An angle that is more than 180 but less than 360is called a reflex angle.
8. Two angles whose sum is 90 are called complementary angles to each other.
9. Two angles whose sum is 180 are called supplementary angles to each other.
10. Two angles are called adjacent angles if they have a common vertex, a common arm and their non
common arms are on the different sides of the common arm.
11. When the sum of two adjacent angles is 180, then together they are called a linear pair of angles.
12. When two lines intersect each other, two pairs of angles opposite to each other are obtained. Angles
in each of these pairs are called vertically opposite angles to each other.
13. A line that intersects two or more lines at distinct points is called a transversal.
14. Interior angles on the same side of the transversal are called as consecutive interior angles or allied
angles or co-interior angles.

2. MB0906: Lines and Angels
Quick Review
 1350+ Videos;
 Well-detailed solutions to 3500+ problems
 Practice assignments
Get FREE Help in Maths at www.mathbuster.in
 HOTS quizzes
 Self-assessment quizzes
 Model Test Papers
 Expert guidance by mathematicians
Buy Your Online Subscription Today (Starting at Rs. 199 per month) and Enjoy:
24 x 7 x 365 Access
to high quality content to learn, practice and assess.
24 x 7 x 365 Question & Answer Forum
to get the best help for your doubts and difficulties.
Learn math anywhere, anytime with
students from across India and abroad.
© 2013 – 2018, ECPL, New Delhi. This document is part of the MathBuster online education program. All intellectual rights associated to this document directly or indirectly are
owned by ECPL and any reproduction, derivation or distribution of this document in original or modified in full or parts, either in manual or electronic form is prohibited unless a
written approval is obtained. This document has been downloaded from www.mathbuster.in for personal and non-commercial use. For any queries, contact math@elipsis.in
2
Important Facts
1. If a ray stands on a line, then the sum of the two adjacent angles so formed is 180. Conversely, if
the sum of two adjacent angles is 180°, then the non-common arms of the angles form a line.
This property is called as the linear pair axiom.
2. An angle is formed when two rays originate from the same point.
3. If a transversal intersects two parallel lines, then
a. each pair of corresponding angles is equal (corresponding angles axiom),
b. each pair of alternate interior angles is equal,
c. each pair of interior angles on the same side of the transversal is supplementary.
4. If a transversal intersects two lines such that, either
a. any one pair of corresponding angles is equal, or
b. any one pair of alternate interior angles is equal, or
c. any one pair of interior angles on the same side of the transversal is supplementary, then the
lines are parallel.
5. If two lines intersect each other, then the vertically opposite angles are equal.
6. Lines which are parallel to a given line are parallel to each other.
7. The sum of the three angles of a triangle is 180.
8. If a side of a triangle is produced, the exterior angle so formed is equal to the sum of the two interior
opposite angles.
9. Exterior angle of a triangle is greater than either of its interior apposite angles.