What is the distance between the origin of a cartesian coordinate system and the point (-6,7)?
The square of the length of the hypotenuse of a right angled triangle is equal to the sum of the squares of the lengths of the other two sides. In our case, picture a right angled triangle with vertices: (0, 0), (-6, 0) and (-6, 7). We are looking for the distance between (0, 0) and (-6, 7), which is the hypotenuse of the triangle. The two other sides are of length 6 and 7.