Question

On a coordinate grid AB has an end point B at (24,16), the midpoint of AB is P(4,-3), what is the Y-coordinate of point A?

Answer 1

Let's take the `x` and `y` co-ordinates separately

The `x` and `y` of the midpoint are the mean of those of the end points.

If `P` is the midpoint then:

`x_P=(x_A+x_B)/2->4=(x_A+24)/2->x_A=-16`

`y_P=(y_A+y_B)/2->-3=(y_A+16)/2->y_A=-22`