# Math Formulas

A collection of math formulas for lookup and reference.

## Geometry

### Area of Circle

### Area of Parallelogram

### Area of Rectangle

### Area of Trapezoid

The area of a trapezoid is given by its height multiplied by the sum of its top length and bottom length divided by two.

### Area of Triangle

### Circumference of Circle

### Distance Between Two Points

The distance between two points, in two dimensions, is given by solving pythagorean's theorem for the length the hypotenuse of the right triangle formed by the two points.

### Midpoint

To find the midpoint between two points, average the two points x coordinate together to get the midpoint's x coordinate, then average the two points y coordinate together to get the midpoints y coordinate.

### Perimeter of two to the n Sided Polygon

To find the perimeter of a polygon with two to the n sides, we can use the recursive formula derived from the special triangle 45 45 90.

### Pythagorean Theorem

The pythagorean theorem is a formula that equates the square of the sides of a right triangle together.

### Volume of Cone

The volume of a cone is given by one third multiplied by PI, the radius of its base squared, and its height.

### Volume of Cube

The volume of a cube is given by the length of the cube length raised to the third power.

### Volume of Cylinder

The volume of a cylinder is equal to PI multiplied by its radius squared and its height.

### Volume of Rectangular Prism

The volume of a Rectangular Prism is equal to its width multiplied by its height multiplied by its length.

### Volume of Sphere

The volume of a sphere is equal to four over three multiplied by PI and its radius cubed.

## Trigonometry

### Law of Cosines

### Law of Sines

### Pythagorean Identity

The pythagorean identity is one equal to cosine squared of theta plus sine squared of theta.

### Pythagorean Theorem

The pythagorean theorem is a formula that equates the square of the sides of a right triangle together.

## Algebra

### Quadratic

The Quadratic formula solves for the x-intercepts of any quadratic equation.

### Slope

The slope of a line is given by the change in y over the change in x.

## Probability

### Combination

The combination formula describes the possible combinations of r elements out of a group of n elements where order does not matter.

### Permutation

The permutation formula describes the possible permutations of r elements out of a group of n elements where order does matter.

### Conditional Probability

The conditional probility formula shows how to calculate the probability of a event B, given that another event A has already occured.

## Linear algebra

### 2x2 Determinant

The formula for the determinant of a two by two matrix.

### 3x3 Determinant

The formula for the determinant of a three by three matrix.