Circle area
A = πr²
Circle circumference
C = 2πr
Rectangle area
A = ℓw
Triangle area
A = ½bh
Pythagorean theorem
a² + b² = c²
Sphere volume
V = 4/3·πr³
Cylinder volume
V = πr²h
Cone volume
V = 1/3·πr²h
The number of degrees of arc in a circle is 360. The number of radians of arc in a circle is 2π. The sum of the measures in degrees of the angles of a triangle is 180.