Unit 4 Vocabulary

Concurrent

• When two lines intersect at a single point.

• When three or more lines intersect at a single point.

• When lines are parallel and never meet.

• When lines intersect at different angles.

Obtuse Triangle

• A triangle with one angle greater than 90 degrees.

• A triangle with all angles less than 90 degrees.

• A triangle with one angle equal to 90 degrees.

• A triangle with all sides equal.

Right Triangle

• A triangle with one 90-degree angle.

• A triangle with all sides equal.

• A triangle with two equal sides.

• A triangle with no equal sides.

Incenter

• The point of concurrency of the angle bisectors of a triangle.

• The center of a triangle's circumcircle.

• The point where the altitudes of a triangle intersect.

• The midpoint of the longest side of a triangle.

Remote Interior Angles

• The angles formed by the intersection of two lines.

• The two non-adjacent interior angles corresponding to an exterior angle of a triangle.

• The angles opposite to each other when two lines intersect.

• The angles that are adjacent to each other in a triangle.

Equiangular Triangle

• A triangle where all angles are equal.

• A triangle with one right angle.

• A triangle with all sides of different lengths.

• A triangle that has at least one obtuse angle.

Isosceles Triangle Vertex Angle Conjecture

• The vertex angle of an isosceles triangle is bisected by the altitude to the base.

• The base angles of an isosceles triangle are equal.

• The sum of the angles in an isosceles triangle is 180 degrees.

• The altitude to the base is always longer than the sides.

Converse of the Angle Bisector Theorem

• If a point is equidistant from the sides of an angle, it lies on the bisector of the angle.

• If a point lies on the bisector of an angle, it is equidistant from the sides of the angle.

• If a point is not equidistant from the sides of an angle, it lies on the bisector of the angle.

• If a point lies outside the angle, it is equidistant from the sides of the angle.

Base Angles (isosceles triangle)

• The angles opposite the legs (two congruent sides) of an isosceles triangle.

• The angles adjacent to the base of an isosceles triangle.

• The angles formed by the intersection of the height and the base of an isosceles triangle.

• The angles that are equal in an equilateral triangle.

Acute Triangle

• A triangle where all interior angles are less than 90 degrees.

• A triangle with one angle greater than 90 degrees.

• A triangle with all sides equal in length.

• A triangle where one angle is exactly 90 degrees.