ACT Math Formulas

one

100

Area of a triangle

A=1/2bh or (bh)/2

200

Surface area of a cylindar

2pir^2+pidh

300

Vertex x-coordinate of a parabola

x=(-b)/(2a)

400

Area of a rectangle

A=lw

500

Quadratic formula

x=-b+-sqrt[(b^2-4ac)]/(2a)

two

100

Slope formula

M=(y₂-y₁)/(x₂-x₁)

200

Cosecant (reciprocal of sine)

csctheta

1/sintheta

300

Area of a circle

A=pir^2

400

Midpoint formula

[(x₁+x₂)/2, (y₁+y₂)/2]

500

Area of a trapezoid

A={(b₁+b₂)h}/2

three

100

Simple interest formula

I=prt

200

Volume of a cylindar

V=pir^2(h)

300

Standard form of a quadratic equation

ax^2+bx+c=0

400

Slope-intercept form of a line

y=mx+b

500

Equation of a circle

(x-h)^2+(y-k)^2=r^2

four

100

Circumference of a circle

C=pid or C=2pir

200

Formula for an arithmetic sequance

a_n=a₁+(n-1)d

300

Point-slope form of a line 

y-y₁=m(x-x₁)

400

The sum of the interior angles of a polygon

(n-2)(180)

500

Pythagorean Theorem

a^2+b^2=c^2

five

100

Secant (reciprocal of cosine)

sectheta

1/costheta

200

Volume of a rectangular prism

V=lwh

300

Cotangent (reciprocal of tangent)

cottheta

1/tantheta

400

Surface area of a rectangular prism

SA=2lw+2lh+2wh

500

Distance formula

d=sqrt[(x₂-x₁)^2+(y₂-y₁)^2