## A–F

AA similarity theorem
Unit 6 Lesson 3

Two triangles are similar if they have two corresponding angles that are congruent.

absolute value
Unit 4 Lesson 3

A number’s distance from zero on the number line.

The symbol means the absolute value of .

Recall that distance is always positive.

The diagram shows that and .

absolute value function
Unit 4 Lesson 3

A function that contains an algebraic expression within absolute value symbols. The absolute value parent function, written as:

Unit 5 Lesson 6

Two non-overlapping angles with a common vertex and one common side.

alternate exterior angles
Unit 5 Lesson 6

A pair of angles formed by a transversal intersecting two lines. The angles lie outside of the two lines and are on opposite sides of the transversal.

See angles made by a transversal.

alternate interior angles
Unit 5 Lesson 6

A pair of angles formed by a transversal intersecting two lines. The angles lie between the two lines and are on opposite sides of the transversal.

Altitude of a triangle:

A perpendicular segment from a vertex to the line containing the base.

Altitude of a solid:

A perpendicular segment from a vertex to the plane containing the base.

Two rays that share a common endpoint called the vertex of the angle.

angle bisector
Unit 5 Lesson 4

A ray that has its endpoint at the vertex of the angle and divides the angle into two congruent angles.

angle of depression/angle of elevation
Unit 6 Lesson 9

Angle of depression: the angle formed by a horizontal line and the line of sight of a viewer looking down. Sometimes called the angle of decline.

Angle of elevation: the angle formed by a horizontal line and the line of sight of a viewer looking up. Sometimes called the angle of incline.

angles associated with circles: central angle, inscribed angle, circumscribed angle
Unit 7 Lesson 1, Unit 7 Lesson 4

Central angle: An angle whose vertex is at the center of a circle and whose sides pass through a pair of points on the circle.

Inscribed angle: An angle formed when two secant lines, or a secant and tangent line, intersect at a point on a circle.

Circumscribed angle: The angle made by two intersecting tangent lines to a circle.

Unit 5 Lesson 6

The distance along the arc of a circle. Part of the circumference.

Equation for finding arc length: