ACT Math Vocabulary Review

Taken from the Princeton Review ACT prep 2023.

Area of a circle

πr²

Circumference of a circle equation.

2πr

Supplementary angles

Angles that add up to 180 degrees.

Vertical angles

Angles that are opposite from each other and always equal each other.

A 3-4-5 triangle and it’s multiples (6-8-10, 9-12-15, 15-20-25) can only be used on…

Right triangles.

The 45-45-90 triangle with two equivalent side lengths and a hypotenuse that equals the side length times root 2 is called…

Isosceles right triangle.

The 30-60-90 right triangle.

The length of the short side of the 30-60-90 triangle is…

half the length of the hypotenuse; the hypotenuse is twice as long.

The length of the medium side of the 30-60-90 triangle is…

equal to the length of the short side times root 3.

The length of the hypotenuse of the 30-60-90 triangle is…

twice as long as the length of the short side.

Area of a triangle equation

A = 1/2(bh)

Distance formula

root(x2 - x1)²+(y2-y1)²

Equation of a circle

(x-h)²+(y-k)²=r²

Equation of an eclipse

[(x-h)²/a²]+[(y-k)²/b²]=1

The center of a circle

(h,k)

Cosecant is…

1/sine

Secant is…

1/cosine

Cotangent is…

1/tangent

Sine theta divided by cos theta is equal to…

tan theta

Sine² theta plus cos² theta is equal to…

1

Quadrant I, angle 90 to angle 0, 360 equal to 0, pi/2 contains…

all positive values.

Quadrant II, angle 90 to angle 180 equal to pi contains…

a positive sine ratio

Quadrant III, angle 180 to angle 270, equal to 3pi/2 contains…

a positive tangent ratio.

Quadrant IV, angle 360 to angle 270, equal to 2pi contains…

a positive cosine ratio

In a unit circle, cosine represents the…

x axis.

In a unit circle, sine represents the…

y axis

logba = x is equal to…

b^x = a

In a vector, i indicates…

horizontal change

In a vector, j indicates…

vertical change

Real numbers are…

Numbers that can be represented IRL. ex: 1, 2, .5, 10, 4

Integers are…

Whole numbers from -infinity to +infinity.

Whole numbers are…

Non decimal numbers from 0 to infinity.

Rational numbers are…

Numbers that can be represented as a fraction, including integers and repeating decimals.

Irrational numbers are…

Real numbers that cannot be written as a fraction.