Distance Formula
The Distance Formula
can be used to find the distance between two points.
d = 
(x1, y1)
(x- x1)2 + (y- y1)2
(x2, y2)
A line segment is graphed on the coordinate plane. The distance between the points can be found using the Distance Formula.
(-4 , 1)
(2 , 3)
Check each step of the work.
Then hit OK.
The work is shown below to find the distance between
the points shown.
(-4 , 1)
x1
y1
d = 
x2
(2 , 3)
62 + 22
(2 - -4)2 + (3 - 1)2
y2
(x- x1)2 + (y- y1)2
=    40 
The exact distance between the points is √40. Round the distance to the nearest tenth.Use a calculator.
(-4 , 1)
√40 ≈            units
(2 , 3)
Your Turn! Find the distance between the points.
Start by writing the coordinates.
(
,
)
(
,
)
Drag the appropriate 
notation onto the diagram.
(
x1
?
2
,
1
y1
)
(
x2
5
,
y2
?
4
)
d = 
Plug the values into 
the distance formula.
(     –     )2 + (     –     )2
(x- x1)2 + (y- y1)2
(
x1
2
,
1
y1
)
(
x2
5
,
4
y2
)
d = 
Simplify under the radical
(5 – 2)2 + ( 4 – 1)2
     2  +      2 
(x- x1)2 + (y- y1)2
(
x1
2
,
1
y1
)
(
x2
5
,
4
y2
)
d = 
Continue to simplify.
(5 – 2)2 + ( 4 – 1)2
32 + 32 
(x- x1)2 + (y- y1)2
+
(
x1
2
,
1
y1
)
(
x2
5
,
4
y2
)
d = 
Write the exact answer asa radical.
(5 – 2)2 + ( 4 – 1)2
9 + 9
32 + 32 
(x- x1)2 + (y- y1)2
= √
(
x1
2
,
1
y1
)
(
x2
5
,
4
y2
)
d = 
Round to the nearest tenth.
(5 – 2)2 + ( 4 – 1)2
9 + 9
32 + 32 
(x- x1)2 + (y- y1)2
= √
18
(
Round to the nearest tenth:
√18 ≈
x1
2
,
1
y1
)
(
x2
5
,
4
y2
)
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