Find the other endpoint of the line segment with the given endpoint and midpoint. - Show Work

Question

Endpoint: (3,3), midpoint: (6,9) 

Answer 1

We know how to find the midpoint coordinates by the following:

(a + b) / 2 = c, where a and b are the endpoints and c is the midpoint.

 

Well, in this case, instead of a and b and finding c, we have a and c, and need to find b. First the x-coordinate:

(3 + b) / 2 = 6

multiply both sides by 2:

3 + b = 12

Subtract both sides by 3:

b = 9

 

Now the y- coordinate. Follow the same rules as before, start by multiplying by 2:

(3 + b) / 2 = 9

3 + b = 18

Subtract 3:

b = 15

 

So our missing endpoint is (9, 15).