Question

Find the other endpoint given the following Endpoint: (5,-3) Midpoint: (7,-6)

Answer 1

The answer is (9, -9) for The second midpoint.  

Let's start by calling the known endpoint L and the unknown K. We'll call the midpoint M. In order to find this, we must first note that to find a midpoint we need to take the average of the endpoints. To do this we add them together and then divide by 2. So, using that, we can write a formula and solve for each part of the k coordinates. We'll start with just x values.

(Kx + Lx)/2 = Mx

(Kx + 5)/2 = 7

Kx + 5 = 14

Kx = 9

And now we do the same thing for y values

(Ky + Ly)/2 = My

(Ky + -3)/2 = -6

Ky + -3 = -12

Ky = -9

This gives us the final point of (9, -9)