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Unit 7: Geometry
Acute Angle
An angle with a measure greater than 0° and less than 90°.
Adjacent Angles
Two angles that have the same vertex, share a common side, and
do not overlap.
Angle
Two rays with a common endpoint form an angle. The rays and
vertex are used to name an angle. The rays and vertex are used
to name an angle.
Complementary
Angles
Two angles are complementary if the sum of their measures is 90°.
Cone
A solid that has one curved surface, one flat base (usually circular),
and one vertex.
Congruent
Line segments that have the same length, or angles that have the
same measure, or figures that have the same size and shape.
Cylinder
A solid that has two parallel, congruent bases (usually circular)
connected with one curved side and no vertices.
Dilation
A transformation that alters the size of a figure but not its shape.
Edge
Where two planes intersect in a line.
Equilateral
Triangle
A triangle that has three congruent segments.
Faces
A flat surface of a solid figure.
Hypotenuse
The side opposite the right angle.
Unit 7: Geometry
Legs
In a right triangle, the sides adjacent to the right angle.
Line Segment
Part of a line containing two endpoints and all the points between
them.
Obtuse Angle
An angle with a measure greater than 90° but less than 180°.
Parallelogram
A quadrilateral with opposite sides parallel and congruent.
Plane
A two-dimensional flat surface that extends in all directions and
contains at least three non-collinear points.
Point
A specific location in space with no size or shape.
Polygon
A simple closed figure in a plane formed by three or more line
segments.
Polyhedron
A solid with flat surfaces that are polygons.
Prism
A polyhedron with two parallel, congruent polygon bases and
rectangular or square faces.
Pyramid
A polyhedron that has a polygon for a base and triangular faces
that share a common vertex.
Pythagorean
Theorem
If a triangle is a right triangle, then the square of the length of the
hypotenuse is equal to the sum of the squares of the lengths of the
legs or c2 = a2 + b2.
Quadrilateral
Any closed figure with four sides and four vertices, including
squares, rectangles, and trapezoids.
Rectangle
A parallelogram with four right angles.
Unit 7: Geometry
Reflection
A transformation where a figure is flipped over a line. Also called a
flip.
Reflex Angle
An angle with a measure greater than 180° but less than 360°.
Rhombus
A parallelogram with four congruent sides and 2 pairs of congruent
and opposite angles.
Right Angle
An angle with a measure equal to 90°.
Rotation
A transformation where a figure is turned around a fixed point.
Also called a turn.
Similar figures
Figures that have the same shape but not necessarily the same
size.
Skew lines
Lines that are neither intersecting nor parallel. They lie in different
planes.
Straight Angle
An angle with a measure equal to 180°.
Supplementary
Angles
Two angles are supplementary if the sum of their measures is 180°.
Three-Dimensional Three-dimensional figures have three dimensions: length, width,
and depth for height.
Solids
Transformation
A movement of a geometric figure.
Translation
A transformation where a figure is slid from one position to another
without being turned. Also called a slide.
Trapezoid
A quadrilateral with exactly one pair of parallel sides.
Unit 7: Geometry
Vertex
Where three or more planes intersect in a point. Plural: vertices.
Vertical Angles
Two pairs of opposite angles formed by two intersecting lines. The
angles formed are congruent.