ACT math

Law of cosines

a² = b² + c² − 2bc cos(A)

Standard Deviation

How far away everything is from the mean.

Meadin

The middle number

Convert to Radains

X^o*(Pi/180)

Midpoint

(x₁+x₂)/2 visa

Triangel: A

A=1/2bh

Circle: C

C=2pi r

Circ;e: A

A=pi r²

Arch length

θ/360 × 2pir rθ

Sector area

θ/360 *pi r² 1/2r²θ

Cube: V

s³

Cube: SA

6s²

Cylinder: V

πr²h

Cylinder: SA

2πr²+2πrh

Cone: V

1/3πr²

Cone: SA

πr² + πrL

Sphere: V

4/3πr³

Sphere: SA

4πr²

Arithmatic: General Term

a_n=a₁ + (n-1)d

Arthmatic: Sum

S_n = n/2(a₁ +a_n)

Geometric: General Term

a₁ r^n-1

Geometric: Sum

S_n = a₁ (1-rⁿ)/(1-r)

weighted mean

$$\bar{x}=\frac{\sum w_ix_i}{\sum w_i}7$$