ACT Math Formulas

24 Must Know Formulas for the ACT

Slope Intercept Form

y = mx + b

Slope Between Two Points

(y₂ - y₁) / (x₂ - x₁)

Distance Formula

d=√((x₂−x₁)² + (y₂−y₁)²)

Midpoint Formula

((x₁ + x₂)/2), ((y₁ + y₂)/2)

Quadratic Formula

x = (−b ± √(b²−4ac)) / 2a

Discriminant

b² - 4ac

Area of a Triangle

1/2bh

Area of a Trapezoid

1/2(b₁+b₂)*h

Pythagorean Theorum

a² + b² = c²

Special Right Triangle 45-45-90

x : x : x√2

Special Right Triangle 30-60-90

x : x√3 : 2x

Area of Circle

πr²

Circumference of a Circle

2πr (or πd)

Arc Length in a Circle

arc length = (central angle / 360) × 2πr

Sector Area

sector area = (central angle / 360) × πr²

Volume of a Cylinder

V = πr²h

Volume of a Cone

V = (1/3)πr²h

Volume of a Sphere

V = (4/3)πr³

Sin Ratio (SOH)

sin θ = opp / hyp

Cosine Ratio (CAH)

cos θ = adj / hyp

Tangent Ratio (TOA)

tan θ = opp / adj

Mean

Mean = Σ / n

Probaility

P = desired / total