Angle Pairs with Equation

When two parallel lines are cut by a third line, the third line is called TRANSVERSAL.

How many angles are formed when two parallel lines are cut by a transversal line?

Alternate Interior Angles

- these are the angles that are formed on opposite sides of the transversal and inside the two lines

- the theorem says that when the lines are parallel, that the alternate interior angles are equal

Alternate Interior Angles

- these are the angles that are formed on opposite sides of the transversal and inside the two lines

- the theorem says that when the lines are parallel, that the alternate interior angles are equal

Alternate Exterior Angles

- are pairs of opposing angles that are formed when a transversal intersects two lines.



- the theorem says that the pairs of exterior angles formed by a transversal line are congruent.

Alternate Exterior and Interior Angles

Alternate Exterior and Interior Angles

Corresponding Angles

when two parallel lines are intersected by a third one (transversal), the angles that occupy the same relative position at each intersection are known to be corresponding angles to each other.

Corresponding Angles

Corresponding Angles

Consecutive Interior Angles

Two angles on one side of the transversal but inside the parallel lines. Their sum is 180°

∠A + ∠B = 180°
∠C + ∠D = 180°

Find the measurement of the angles

If ∠2 = 53°, then

1. ∠4 = ______
2. ∠7 = ______
3. ∠6 = ______
4. ∠3 = ______
5. ∠5 = ______