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Geometry Vocabulary

Seventh Grade Geometry Vocabulary

Acute Angle An angle whose measure is in between 0 and 90 degrees.
Obtuse Angle An angles whose measure is in between 90 and 180 degrees.
Straight Angle An angle whose measure is exactly 180 degrees.
Right Angle An angle whose measure is exactly 90 degrees.
Complementary Angles When two angles have a sum of 90 degrees.
Supplementary Angles When two angles have a sum of 180 degrees.
Vertical Angles When two angles are formed by intersecting lines, are directly across from each other, and are congruent.
Adjacent Angles When angles are next to each other.
Acute Triangle A triangle whose angles measure 85, 15, and 80 degrees.
Obtuse Triangle A triangle whose angles measure 110, 24, and 46 degrees.
Right Triangle A triangle whose angles measure 62, 90, and 28 degrees.
Scalene Triangle A triangle that has no congruent side lengths.
Isosceles Triangle A triangle that has at lease two congruent sides.
Equilateral Triangle A triangle that has three congruent sides.
Quadrilateral A general name for a four-sided closed figure where all sides are line segments (no curves).
Rectangle A quadrilateral with four 90 degree angles.
Square A quadrilateral with four 90 degree angles and four congruent sides.
Parallelogram A quadrilateral with two pairs of parallel sides.
Rhombus A quadrilateral with four equal sides.
Trapezoid A quadrilateral with exactly one pair of parallel sides.
Pentagon A polygon with five sides.
Hexagon A polygon with six sides.
Heptagon A polygon with seven sides.
Octagon A polygon with eight sides.
Nonagon A polygon with nine sides.
Decagon A polygon with ten sides.
Undecagon A polygon with eleven sides.
Dodecagon A polygon with twelve sides.
Perimeter The linear distance around the outside side lengths of a figure.
Area The amount of squared units that covers the space of a two-dimensional figure.
Surface Area The amount of squared units that cover the area of the faces of a three-dimensional figure.
Volume The amount of cubic units that fill the inside space of a three-dimensional figure.
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