Maths Equations

Speed

Distance/time

Density

Mass/volume

Pressure

Force/area

Percentage change

Change/original amount * 100

Simple interest

Principal*rate*time/100

Gradient of a straight line (m)

y2-y1/x2-x1

Equation of a straight line

y = mx+c

Equation of a circle (centered at origin)

x²+y²= r²

Midpoint of two coordinates

(x1+x2 /2, y1+y2 /2)

Perpendicular line gradients

m1*m2 = - 1

Direct proportion

y = kx

Inverse proportion

y = k/x

Difference of two squares

a²-b² = (a+b) (a-b)

Area of a triangle

0.5 x base x height

Area of a parallelogram

Base x perpendicular height

Circumference of a circle

2*pi*r

Area of a circle

Pi*r²

Arc length of a sector

theta/360 × 2pi*r (circumference of a circle)

Area of a sector

theta/360 x pi*r² (area of a circle)

Volume of a cylinder

Pi*r² *h

Volume of any prism

Area of cross-section * length

Total surface area of a cylinder

2pi*r² + 2pi rh

P(Aand B)

(independent events)

P(A) * P(B)

P(A given B)

(conditional probability)

P(A and B) / P(B)

Estimated mean from grouped frequency tables

fx/f

Frequency density (histograms)

Frequency / class width

Lower quartile

Position= n+1 / 4

Median

Position = n+1 / 2

Upper Quartile

Position = 3(n+1) / 4

x^0

=1

x ^ a/b

x^-a