Angle Formed By Two Lines and a Transversal

In above figure line l, intersects two lines m and n at the point p and q respectively.

Therefore, line l is a “Transversal” for lines m and n.

Four angles are formed at the points p, by line l, name of these angles as ∠1, ∠2, ∠3, and ∠4.

Four angles are formed at the points q, by line l, name of these angles as ∠5, ∠6, ∠7, and ∠8.

These eight angles ∠1, ∠2, ∠3, ∠4, ∠5, ∠6, ∠7 and ∠8 are shown in the above figure.

∠1, ∠2, ∠7 and ∠8 are called “Exterior angles”

∠3, ∠4, ∠5 and ∠6 are called “Interior angles”.

Pairs of angles formed when a transversal intersects two lines.

The pair of alternate interior angles are

(i) ∠4 and ∠6 (ii) ∠3 and ∠5

The pair of alternate exterior angles are

(i) ∠1 and ∠7 (ii) ∠2 and ∠8

Corresponding Angles

The pair of corresponding angles are

(i) ∠1, and ∠5 (ii) ∠2, and ∠6, (iii) ∠4, and ∠8 and (iv) ∠3, and ∠7,

The pair of interior angles on same side of the transversal are

(i) ∠4 and ∠5 (ii) ∠3 and ∠6

MathsMD