# What Is the Distance Formula (Math)?

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The **distance formula **is an equation used to find the distance between any two points on a graph. The distance formula is derived directly from the Pythagorean theorem** **which tells you the length of the hypotenuse *c *if you know the length of each of the other two sides of a triangle.

**Key Points**

- You’ll need to know the full coordinates of two points on a graph to solve for the distance.
- Distance is always expressed as a positive number, even if some or all the coordinates of your points are found in the negative region of the graph.
- It doesn’t matter which points you choose to be the first and second pair because the distance will always come out the same.
- Be sure to pay attention when subtracting negative numbers when solving your equation. Remember that subtracting a negative number is the same as adding the same positive number.
- If the two points lie on the same
*x*or*y*axis, it will often be easier to just find the difference using simple subtraction of the distance between coordinates on that shared axis. When two*x*or two*y*coordinates do not share a common axis you’ll want to use the distance equation. - Be sure not to mix up the coordinates when substituting values into the equation—this is the most common mistake made when solving this equation.
- If your result is the square root of a number such as 4 or 9 that will give a whole number when calculated, remember to use the whole number instead of leaving the answer as a square root. If your answer is a number that does not reduce to a whole number for its square root, leave it as a square root unless asked to write it as a decimal.