Math Review 1.1

The ratio of the circumference of a circle to its diameter.The constant of proportionality between any circle's diameter and circumference.The estimate you need to know for this is 3.14π = C ÷ D

• pi

• radius

• diameter

• area

The distance from the center of a circle to any point on the circle.Half the diameter.r = d ÷ 2r = C ÷ π ÷ 2

• pi

• radius

• diameter

• area

The distance around a circle, like a circle's perimeter.

C=πd

or

C=2πr

• pi

• radius

• diameter

• circumference

A straight line passing through the center of a circle from side to side.Twice the radius.d=2rd = C ÷ π

• pi

• radius

• diameter

• circumference

The number of square units required to cover a surface.

• pi

• radius

• area

• circumference

A=bhbase times height

• area of a rectangle

• radius

• area of a circle

• circumference

The space the inside of a circle takes upA=πr²orA=π•r•r

• area of a rectangle

• radius

• area of a circle

• circumference

A=0.5•b•horA=1/2•b•horA=b•h÷2

• area of a rectangle

• radius

• area of a triangle

• circumference

Sum of a triangle's angles

• 180 degrees

• 90 degrees

• 150 degrees

• area of a triangle

The sum of the lengths of any two sides of a triangle is greater than the length of the third side.For example, 2, 2, 4 cannot be a triangle because 2+2 is not greater than 4.But 2, 2, 3 can be a triangle because 2+2 is greater than 3.

• sides of a triangle

• sides of a rectangle

• 150 degrees

• area of a triangle