Math · K-12

Basic Geometry Facts

Core geometry vocabulary and formulas covering shapes, angles, perimeter, area, and volume for middle school geometry.

40 cards · basic cards · AI-written, checked twice. Edit anything.

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What is an acute angle?
An angle that measures less than 90 degrees.
What is a right angle?
An angle that measures exactly 90 degrees.
What is an obtuse angle?
An angle that measures between 90 and 180 degrees.
What are complementary angles?
Two angles whose measures add up to 90 degrees.
What are supplementary angles?
Two angles whose measures add up to 180 degrees.
What is the sum of all angles in a triangle?
180 degrees.
What is the sum of all angles in a quadrilateral?
360 degrees.
What is perimeter?
The total distance around the outside of a shape.
What is the formula for the area of a rectangle?
length times width, or A = l * w
What is the formula for the area of a triangle?
A = (1/2) * base * height
What is the formula for the area of a circle?
A = pi * r squared, or A = pi * r^2
What is the formula for the circumference of a circle?
C = 2 * pi * r, or C = pi * d
What is the radius of a circle?
The distance from the center to any point on the circle.
What is the diameter of a circle?
The distance across the circle through its center.
State the Pythagorean theorem.
In a right triangle, a squared plus b squared equals c squared, or a^2 + b^2 = c^2

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