Question

Plot point C(2,7). If M is the midpoint of CD , what are the coordinates of D?

Answer 1

Answer:

The coordinates of D is (-4,-9)

Step-by-step explanation:

Given

C = (2,7)

M=(-1,-1)  ----- Missing part of question

Required

Determine the coordinates of D

Let the coordinates of D be (x₂,y₂)

We'll solve this question using mid point formula;

$M(x,y) = (\frac{x_1+x_2}{2},\frac{y_1+y_2}{2})$

Where

$C(x_1,y_1) = (2,7)$    and     $M(x,y) = (-1,-1)$

Put these values in the formula

$(-1,-1) = (\frac{2+x_2}{2},\frac{7+y_2}{2})$

By comparison;

$-1 = \frac{2+x_2}{2}$  and $-1 = \frac{7+y_2}{2}$

$-1 = \frac{2+x_2}{2}$

Multiply both sides by 2

$-2 = 2 + x_2$

Subtract 2 from both sides

$-2 -2 = x_2$

$x_2 = -4$

$-1 = \frac{7+y_2}{2}$

Multiply both sides by 2

$-2 = 7 + y_2$

Subtract 7 from both sides

$-2 - 7 = y_2$

$y_2 = -9$

Hence, the coordinates of D is (-4,-9)