# ACT Math Plane Geometry

Area of a Triangle

A = (1/2)(b)(h)

Area of a Circle

0

Circumference of Circle

0

Perimeter of a Square

P = 4(s)

Area of a Square

0

Area of a Trapazoid

1/2h(a+b)a and b are the two bases

Area of a Rectangle

A = (l)(w)

Perimeter of a Rectangle

0

Properties of a Rectangle

-4 right angles; -Diagonals bisect each other and are congruent; -Opposite sides are equal

Similar Triangles

corresponding angles are equal, corresponding sides are proportionate

Pythagorean Theorem

0

Volume of a Cube

V = s s s

Volume of a Rectangular Solid

0

Surface Area of a Cube

0

Surface Area of a Rectangular Solid

0

Isosceles Triangle

two angles are equal, two sides are equal

Equilateral Triangle

three angles are equal (60 degrees), three sides are equal

Hypotenuse

Longest side in a right triangle, opposite the right angle

Pythagorean Triples

3, 4, 5 ; 5, 12, 13 ; 8, 15, 17 ; 7, 24, 25

Angles in a Triangle

the three interior angles add to 180 degrees

Properties of an Isosceles Trapezoid

-opposite sides are equal; -top two angles are congruent; -bottom two angles are congruent; -diagonals are congruent

Triangle Side Lengths

A side length of a triangle is: (1) greater than the other two sides subtracted; (2) less than the sum of the other two sides

Perpendicular lines

1 point in common, form a right angle, slope are negative reciprocals (i.e. 2/3 and -3/2)

Area of a Parallelogram

A=bh

Bisect

to divide into two equal parts

Chord

a segment whose endpoints are on a circle

arc

Any part of the circumference. The curved portion between the points of a circle.

Colinnear

points on the same line

Sector

The part of a circle that looks like a piece of pie. A sector is bounded by 2 radii and an arc of the circle.

vertex (vertices)

The point at which two lines segments, lines, or rays, meet to form an angle.

Perimeter of a triangle

P=a+b+c

Surface area of a cylinder

SA=2πr²+2πrh

Sum of interior angles in an "n" sided polygon

(n-2)180

Angle measure of a regular polygon

(n-2)180 / n

Volume of a right circular cylinder

V=πr²h