Hi, my name is Bassem Saad. I'm a Math Ph.D. candidate at U.C. Davis and I'm here today for About.com to show you how to use the distance formula.The distance formula can be used to find the distance between any two points on a plane, and it's derived from the Pythagorean Theorem. As you can see, the distance between these two points is just the same as the length of the hypotenuse. And from the Pythagorean Theorem we know that the length of the hypotenuse is just the square root of a squared plus b squared. And from this picture we can see that the length of a is just the change of x, given by x two minus x one. And the length of b is just the change of y, given by y two minus y one. With this formula we can now find the distance between these two points. First we find the change in x as minus four, minus zero, which is just negative four. And the change in y is seven minus ten, which is just negative three. Then we go ahead and take the square root of minus four squared, plus minus three squared. This will equal 16 plus nine, which is 25. And the square root of 25 is just five. So the distance between these two points is five units.The distance formula is important to everyday life. Every GPS unit uses the distance formula to help calculate how far you are from your destination. Auto-cad programmers use the formula to help determine the dimensions of their designs. And you can use the formula to help with all sorts of geometric problems. Thanks for watching, and to learn more, visit us on the web at About.com.

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