Geometry Ch. 3

What are parallel lines?

coplanar lines that do not intersect

What are skew lines?

non-coplanar lines that do not intersect

What is a transversal?

a line that intersects 2 or more coplanar lines at different points

Alternate Interior Angles

Two nonadjacent interior angles on opposite sides of the transversal

Same-side Interior Angles

two interior angles on the same side of the transversal

Corresponding Angles

two angles in corresponding positions relative to the two lines

5 ways to prove lines parallel:

1. a pair of corresponding angles are congruent.

2. a pair of alternate interior angles are congruent.

3. a pair of same-side interior angles are supplementary.

4. both lines are perpendicular to a third line. 

5. both lines are parallel to a third line. 

what is the sum of all angle measures in a triangle?

180°

The measure of an exterior angle of a triangle equals:

the sum of the measures of the two remote interior angles

The sum of the measures of the exterior angles of any convex polygon is: 

360°

formula for the measure of an interior angle of a regular polygon

((n-2)x180)/n

formula for the measure of the total angles of the interior of a polygon

(n-2)180