Glossary

area

Area is the number of square units that cover a two-dimensional region, without any gaps or overlaps.

For example, the area of region A is 8 square units. The area of the shaded region of B is 1/2 square unit.

area of a circle

If the radius of a circle is r units, then the area of the circle is πr^2  square units.

For example, a circle has radius 3 inches. Its area is π3^2  square inches, or 9π square inches, which is approximately 28.3 square inches.

base (of a prism or pyramid)

The word base can also refer to a face of a polyhedron.

A prism has two identical bases that are parallel. A pyramid has one base.

A prism or pyramid is named for the shape of its base.

chance experiment

A chance experiment is something you can do over and over again, and you don’t know what will happen each time.

For example, each time you spin the spinner, it could land on red, yellow, blue, or green.

circle

A circle is made out of all the points that are the same distance from a given point.

For example, every point on this circle is 5 cm away from point A, which is the center of the circle.

circumference

The circumference of a circle is the distance around the circle. If you imagine the circle as a piece of string, it is the length of the string. If the circle has radius r then the circumference is 2πr.

The circumference of a circle of radius 3 is 2π3, which is 6π, or about 18.85. 

complementary

Complementary angles have measures that add up to 90 degrees.

For example, a 15° angle and a 75° angle are complementary.

constant of proportionality

In a proportional relationship, the values for one quantity are each multiplied by the same number to get the values for the other quantity. This number is called the constant of proportionality.

coordinate plane

The coordinate plane is a system for telling where points are. For example point R is located at (3,2)  on the coordinate plane, because it is three units to the right and two units up.

corresponding

When part of an original figure matches up with part of a copy, we call them corresponding parts. These could be points, segments, angles, or distances.

For example, point B in the first triangle corresponds to point E in the second triangle. Segment  AC corresponds to segment DF.

cross section

A cross section is the new face you see when you slice through a three-dimensional figure.

For example, if you slice a rectangular pyramid parallel to the base, you get a smaller rectangle as the cross section.

deposit

When you put money into an account, it is called a deposit.

For example, a person added $60 to their bank account. Before the deposit, they had $435. After the deposit, they had $495, because 435+60=495.

equivalent expressions

Equivalent expressions are always equal to each other. If the expressions have variables, they are equal whenever the same value is used for the variable in each expression.

For example, 3x+4x is equivalent to 5x+2x. No matter what value we use for x, these expressions are always equal. When x is 3, both expressions equal 21. When x is 10, both expressions equal 70.

equivalent ratios

Two ratios are equivalent if you can multiply each of the numbers in the first ratio by the same factor to get the numbers in the second ratio. For example, 8:6 is equivalent to 4:3, because 8*1/2=4 and 6*1/2=3.

expand

To expand an expression, we use the distributive property to rewrite a product as a sum. The new expression is equivalent to the original expression.

For example, we can expand the expression 5(4x+7) to get the equivalent expression 20x+35.

factor (an expression)

To factor an expression, we use the distributive property to rewrite a sum as a product. The new expression is equivalent to the original expression.

For example, we can factor the expression 20x+354 to get the equivalent expression 5(4x+7).

interquartile range (IQR)

The interquartile range is one way to measure how spread out a data set is. We sometimes call this the IQR. To find the interquartile range we subtract the first quartile from the third quartile.

For example, the IQR of this data set is 20 because 50+30=20.