Triangles and Congruence Unit 7

Scalene Triangle

A triangle with NO congruent sides

Isosceles Triangle

A triangle with TWO congruent sides

Equilateral Triangle

A triangle with THREE congruent sides.

Acute Triangle

A triangle with THREE acute angles

Obtuse Triangle

A triangle with ONE obtuse angle

Right Triangle

A triangle with ONE right angle

Equiangular Triangle

A triangle with THREE congruent angles.

Right-Scalene

Give one angle classification and one side classification for the given triangle.

Acute-Scalene

Give one angle classification and one side classification for the given triangle.

Obtuse-Scalene

Give one angle classification and one side classification for the given triangle.

Right-Isosceles

Give one angle classification and one side classification for the given triangle.

Acute-Isosceles

Give one angle classification and one side classification for the given triangle.

Obtuse-Isosceles

Give one angle classification and one side classification for the given triangle.

Equiangular-Equilateral

Give one angle classification and one side classification for the given triangle.

Parallel Lines

lines in the same plane that never intersect

Transversal

a line that intersects two or more lines

Corresponding Angles

Angles formed by a transversal cutting through 2 or more lines that are in the same relative position. If lines are parallel, these angles are congruent.

Alternate Interior Angles

Angles that are non-adjacent interior angles that lie on OPPOSITE sides of the transversal. If the lines are parallel, these angles are congruent.

Alternate Exterior Angles

Angles that are non-adjacent exterior angles that lie on OPPOSITE sides of the transversal. If lines are parallel, these angles are congruent.

Same Side Interior Angles

Angles that are non-adjacent interior angles that lie on the SAME side of the transversal. If lines are parallel, these angles are supplementary.

Interior Angles

Angles that lie in between the lines that are cut by the transversal

Exterior Angles

Angles that lie outside of both the lines that are cut by the transversal

collinear

Points that lie on the same line

coplanar

Points that lie in the same plane

endpoint

a point at one end of a segment or the starting point of a ray.

line

a straight path that has no thickness and extends forever.

Congruent

same shape and size

plane

a flat surface that has no thickness and extends forever.

point

a location and has no size. It is represented by a dot.

postulate

or axiom, is a statement that is accepted as true without proof.

ray

a part of a line that starts at an endpoint and extends forever in one direction.

segment

the part of a line consisting of two points and all points between them.

undefined terms

cannot be defined by using other figures.

Equal

same in value

distance

the absolute value of the differenceof the coordinates

length

distance between A and B ΜΆΜΆ

congruent segments

segments that have the same length

skew

two lines not parallel or two lines that do not intersect

midpoint

the point that bisects the segment into two congruent segments. the center point

bisect

divides

segment bisector

any ray, segment, or line that intersects a segment at its midpoint. It divides a segment into two equal parts at its midpoint.

angle

a figure formed by two rays, or sides, with a common endpoint

vertex

common endpoint

interior of an angle

The set of all points between the sides of the angle

exterior of an angle

the set of all points outside the angle.

measure

usually given in degrees.

degree

1 out of 360 of a circle

acute angle

an angle less then 90 degrees

right angle

a 90 degree angle

obtuse angle

an angle more then 90 degrees

straight angle

a 180 degree angle

congruent angles

angles that have the same measures

angle bisector

the line segment, line, or ray that bisects an angle

adjacent angles

two angles in the same plane with a common vertex and a common side, but no common interior points.

linear pair

a pair of adjacent angles whose noncommon sides are opposite rays

complementary angles

angles that add up to 90 degrees

supplementary angles

angles that add up to 180 degrees

vertical angles

two nonadjacent angles formed by two intersecting lines. opposite angles

coordinate plane

a plane that is divided into four regions by a horizontal line (x-axis) and a vertical line (y-axis)

intersection

the point where two lines meet

Transversal

line that intersects through two parallel lines

Perpendicular

lines that intersect to create 90 degree angles

Parallel

Lines that never intersect

oblique

neither parallel or perpendicular

Theorem

a statement that follows logically from definitions and principals