RBSE Class 7 Maths Notes Chapter 5 Lines and Angles

These comprehensive RBSE Class 7 Maths Notes Chapter 5 Lines and Angles will give a brief overview of all the concepts.

RBSE Class 7 Maths Chapter 5 Notes Lines and Angles

→ A line-segment has two end points.

→ A ray has only one end point (its vertex).

→ A line has no end points on either side.

→ An angle is formed when two lines, rays or line-segment meet.

→ If measure of two angles is 900, they are called complementary angles.

→ If measure of two angles is 180°, they are called supplementary angles.

→ Two angles are called adjacent angles if they have a common vertex and a common arm but no common interior.

→ Two adjacent angles form a linear pair if their non-common arms are two opposite rays to each other. 

→ When two lines l and m meet, we say they intersect and the meeting point is called the point of intersection.

→ When lines drawn on a sheet of paper do not meet, however for produced, we call them to be parallel lines.

→ When two lines intersect (looking like the letter X) we have two pairs of opposite angles. They are called vertically opposite angles. They are equal in measure.

→ A transversal is a line that intersects two or more lines at distinct points.

→ A transversal gives rise to several types of angles.

→ When a transversal cuts two parallel lines, we have the following interesting relationship :

Each pair of corresponding angles are equal:
∠1 = ∠5, ∠3 =∠7, ∠2 = ∠6, ∠4 = ∠8
Each pair of alternate interior angles are equal:
∠3 = ∠6, ∠4 = ∠5
Each pair of interior angles on the same side of transversal are supplementary :
∠3 + ∠5 = 180°, ∠4 + ∠6 = 180°