Geometry Unit 2 Vocabulary Review

Alternate Interior Angles

nonadjacent angles that lie on opposite sides of the transversal between the intersected line

Alternate Exterior Angles

lie on opposite sides of the transversal and outside the intersected lines

Same Side Interior Angles

lie on the same side of the transversal and in between the intersected lines

Corresponding Angles

lie on the same side of the transversal and on the same sides of the intersected lines

Remote Interior Angle

an interior angle of a triangle that is not adjacent to the exterior angle

Base of an isosceles triangle

the side opposite the vertex angle in an isosceles triangle

Base Angles of an isosceles triangle

the angles that have the base as a side

Vertex Angle

the angle formed by the legs of a triangle

Isosceles Triangle

A triangle with at least two congruent sides

Equilateral Triangle

A triangle with three congruent sides

Median

a segment whose endpoints are a vertex of a triangle and the midpoint of the opposite side

Circumcenter

the point of concurrency of the three perpendicular bisectors of a triangle

Incenter

the point of concurrency of the three angle bisectors of a triangle

Centroid

the intersection of the three medians of a triangle

Altitude

a perpendicular segment from a vertex to the line containing the opposite side

Hypotenuse

The side opposite the right angle in a right triangle.

Legs

the two sides that form the sides of a right angle in a right triangle

Midsegment

a line segment that connects the midpoints of two sides of a triangle

Point of Concurrency

the intersection of concurrent lines

Transversal

a line that intersects at least two coplanar lines at two or more points

Sum of interior angles in a polygon

(n-2) times 180, n is the number of sides

Triangle Sum Theorem

The sum of the angle measurements in a triangle is 180 degrees.

Triangle Midsegment Theorem

The midsegment of a triangle is parallel to the third side and half of the length of the third side.

Slope of parallel lines

the same slope

Slope of perpendicular lines

opposite reciprocal slopes

Regular polygon

A polygon with equal angles and equal sides.

Sum of exterior angles of a polygon

360 degrees always

Triangle Inequality Theorem

The sum of the lengths of any two sides of a triangle is greater than the length of the third side.

Side-Angle Relationship in Triangles

the bigger angle is opposite the longer side and the smaller angle is opposite the shorter side.

Angle-Side Relationship in Triangles

the longer side is opposite the bigger angle and the shorter side is opposite the smaller angle.

Exterior Angle Theorem for Triangles

the measure of an exterior angle is equal to the sum of the measures of the remote interior angles.