Angle Pairs Boulder CO

A transversal is any line that intersects two or more lines in the same plane but at different points. In Figure 1 , line t is a transversal.

Figure 1 A transversal intersecting two lines in the same plane.

A transversal that intersects two lines forms eight angles; certain pairs of these angles are given special names. They are as follows:

• Corresponding angles are the angles that appear to be in the same relative position in each group of four angles. In Figure 2 , ∠l and ∠5 are corresponding angles. Other pairs of corresponding angles in Figure 2 are: ∠4 and ∠8, ∠2 and ∠6, and ∠3 and ∠7.
  
  

  Figure 2 A transversal intersecting two lines and forming various pairs of corresponding angles—alternate interior angles, alternate exterior angles, consecutive interior angles, and consecutive exterior angles.

• Alternate interior angles are angles within the lines being intersected, on opposite sides of the transversal, and are not adjacent. In Figure 2 , ∠4 and ∠6 are alternate interior angles. Also, ∠3 and ∠5 are alternate interior angles.

• Alternate exterior angles are angles outside the lines being intersected, on opposite sides of the transversal, and are not adjacent. In Figure 2 , ∠l and ∠7 are alternate exterior angles. Also, ∠2 and ∠8 are alternate exterior angles.

• Consecutive interior angles (same-side interior angles) are interior angles on the same side of the transversal. In Figure 2 , ∠4 and ∠5 are consecutive interior angles. Also, ∠3 and ∠6 are consecutive interior angles.

• Consecutive exterior angles (same-side exterior angles) are exterior angles on the same side of the transversal. In Figure 2 , ∠l and ∠8 are consecutive exterior angles. Also, ∠2 and ∠7 are consecutive exterior angles.

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