Midpoint Formula

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SAT Math › Midpoint Formula

Questions 1 - 10

1

Find the midpoint of the line that passes through the points and .

Explanation

Recall the midpoint formula as $(\frac{x1+x2}{2}, \frac{y1+y2}{2})$ .

Thus,

$(\frac{2+(-2)}{2},\frac{-1+1}{2}) = (0,0)$

2

Find the midpoint of the line segment with endpoints and .

$\left (6.35, 2.85 \right )$

$\left (6.35, 2.85 \right )$

$\left (-1.8, 5.3 \right )$

$\left (-1.8, 5.3 \right )$

$\left (1.8, -5.3 \right )$

$\left (1.8, -5.3 \right )$

Explanation

Use the midpoint formula:

$\left ( \frac{x_{1}+x_{2}}{2}, \frac{y_{1}+y_{2}}{2}} \right )$

Substitute:

$\frac{x_{1}+x_{2}}{2} =\frac{3.6+7.2}{2} = \frac{10.8}{2} = 5.4$

$\frac{y_{1}+y_{2}}{2}} \right = \frac{9.1+(-1.5)}{2}} = \frac{7.6}{2} = 3.8$

The midpoint is

3

What is the midpoint of a line that connects the points and ?

Explanation

The midpoint formula is $\left(\frac{x_{1}+x_{2}}{2},\frac{y_{1}+y_{2}}{2}\right)$ .

Therefore, all we need to do is plug in the points given to us to find the midpoint.

In this case, $x_{1}=1,x_{2}=-7,y_{1}=5,y_{2}=9$ .

To find the -value for the midpoint, we add: . Then we divide by : .

To find the -value for the midpoint, we add: . Then we divide by : .

So our solution is .

4

What is the coordinates of the point exactly half way between (-2, -3) and (5, 7)?

$\left(\frac{3}{2}, 2\right)$

$\left(2, \frac{-3}{2}\right)$

Explanation

We need to use the midpoint formula to solve this question.

$midpoint=(\frac{x_1+x_2}{2}, \frac{y_1+y_2}{2})$

In our case

and

Therefore, substituting these values in we get the following:

$midpoint=(\frac{-2+5}{2}, \frac{-3+7}{2})$

$midpoint= (\frac{3}{2}, \frac{4}{2})$

$(\frac{3}{2}, 2)$

5

Find the midpoint of the line that passes through the points and .

Explanation

Recall the midpoint formula as $(\frac{x1+x2}{2}, \frac{y1+y2}{2})$ .

Thus,

$(\frac{-1+5}{2},\frac{4+2}{2}) = (2,3)$

6

Find the midpoint of a line with the endpoings (3, 4) and (-1, -1).

$\left(1, \frac{3}{2}\right)$

$\left(\frac{3}{2}, 1\right)$

Explanation

When finding the midpoint between two points, we use the midpoint formula

$\left(\frac{x_1 + x_2}{2}, \frac{y_1+y_2}{2}\right)$

where and are the points given.

Knowing this, we can substitute the values into the formula. We get

$\left(\frac{3 + -1}{2}, \frac{4 + - 1}{2}\right)$

$\left(\frac{3-1}{2}, \frac{4-1}{2}\right)$

$\left(\frac{2}{2}, \frac{3}{2}\right)$

$\left(1, \frac{3}{2}\right)$

Therefore, $\left(1, \frac{3}{2}\right)$ is the midpoint.

7

Find the point halfway between points A and B.

Explanation

Find the point halfway between points A and B.

We are going to need to use midpoint formula. If you ever have difficulty recalling midpoint formula, try to recall that it is basically taking two averages. One average is the average of your x values, the other average is the average of your y values.

$Mid=(\frac{x_1+x_2}{2},\frac{y_1+y_2}{2})$

Now we plug and chug!

$Mid=(\frac{19+67}{2},\frac{54+34}{2})=(\frac{86}{2},\frac{88}{2})=(43,44)$

So our answer is (43,44)

8

What is the midpoint between $\left ( 2,3\right )$ and $\left ( -7,4\right )$ ?

$\left(\frac{-5}{2}, \frac{7}{2}\right)$

Explanation

The formula to find the midpoint is as follows:

$\left(\frac{x_1+x_2}{2}, \frac{y_1+y_2}{2}\right)$

In our case our

our

substituting in these values we get

midpoint = $\left(\frac{2+-7}{2}, \frac{3+4}{2}\right)=\left(\frac{-5}{2}, \frac{7}{2}\right)$

9

Find the midpoint between and .

$(\frac{1}{2}, 6)$

$(\frac{1}{2}, -3)$

$(\frac{3}{2}, -3)$

$(\frac{3}{2}, 3)$

$(\frac{1}{2}, -6)$

Explanation

Write the midpoint formula.

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

Substitute the points.

$M = (\frac{2+(-1)}{2}, \frac{3+9}{2}) = (\frac{1}{2}, 6)$

The answer is: $(\frac{1}{2}, 6)$

10

Find the midpoint between and .

Explanation

Write the formula for the midpoint.

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

Substitute the point into the formula.

$M = (\frac{-1+3}{2},\frac{-3+(-1)}{2} ) = (1,-2)$

The answer is:

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