Chapter 9: Parallel Lines Flashcards
Transversal
A line that intersects two other coplanar lines in two different points
Parallel Lines
Lines that do not intersect
2 types:
Lines that have no points in common
Line that have all points in common
Alternate Interior Angles
Opposite sides of the transversal
Congruent
Alternate Exterior Angles
Opposite sides of the transversal
Congruent
Corresponding Angles
One interior and one exterior angle that are on the same side of the transversal
Congruent
Interior Angles on the Same Side of the Transversal
Supplementary
If two coplanar lines are each perpendicular to the same line, then they are
Parallel
Two coplanar lines cut by a transversal are parallel if and only if
the alternate interior angles formed are congruent
If two parallel lines are cut by a transversal
then the corresponding angles are congruent
If two of three lines in the same plane are each parallel to the third line
then they are parallel to each other
If two non-vertical lines in the same plane are parallel
then they have the same slope
The sum of the measures of the angles of a triangle is
180
The sum of the measures of the angles of a quadrilateral is
360
The measure of an exterior angle of a triangle is equal to the sum
of the measures of the nonadjacent angles
Isosceles Triangle Theorem
If two sides of a triangle are congruent then the angles opposite these sides are congruent
Polygon
A closed figure that is the union of line segments in a plane
Convex Polygon
A polygon in which each of the interior angles measures less than 180 degrees
Concave Polygon
A polygon in which at least one interior angle measures more than 180 degrees
Consecutive
Next to (adjacent)
Diagonal
A line segment whose endpoint are two nonadjacent vertices
The sum of the measures of the interior angles of a polygon of n sides is
180(n-2)
Regular Polygon
A polygon that is both equilateral and equiangular
Angle, Angle, Side
If two angles and the side opposite one of them in one triangle are congruent to the corresponding angles and the side in another triangle, then the triangles are congruent
Hypotenuse - Leg
If the hypotenuse and a leg of one triangle are congruent to the corresponding parts of the other, then the two RIGHT TRIANGLES are congruent
