Question

Question #93bc7

Answer 1

When you have two cooridnates (`x_1,y_1`) and (`x_2,y_2`), and you want to find `M`, the midpoint, you use the formula
`M=(x_M,y_M)`, where
`x_M= (x_1+x_2)/2`, and `y_M=(y_1+y_2)/2`.

By moving that formula around, you get
`x_2=2x_M-x_1`, and `y_2=2y_M-y_1`. We know that (`x_M,y_M`) equals (`3,1`), and that (`x_1,y_1`) equals (`-1,6`), so we simply plug in the values into the formulas to get

`2*3+1=x_1`
`6+1=x_1`
`7=x_1`

and

`1*2-6=y_2`
`2-6=y_2`
`-4=y_2`

Therefore, (`x_2,y_2`) equals (`7,-4`).

I hope I helped!