Big Ideas Math Integrated I, 2016
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Big Ideas Math Integrated I, 2016 View details
3. Using Midpoint and Distance Formulas
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Exercise 23 Page 401

Use the Distance Formula.

10

Practice makes perfect
To find the distance between two points with known coordinates, we can use the Distance Formula. Let A( x_1, y_1) and B( x_2, y_2) be two points in the coordinate plane. Then, the distance between these two points AB can be calculated as follows. AB=sqrt(( x_2- x_1)^2+( y_2- y_1)^2) Now, we are asked to calculate the distance between points A(13,2) and B(7,10). Let's substitute the coordinates of these points into the Distance Formula.
AB = sqrt((x_2-x_1)^2 + (y_2-y_1)^2)
AB=sqrt(( 7- 13)^2+( 10- 2)^2)
AB=sqrt((- 6)^2+8^2)
AB=sqrt(36+64)
AB=sqrt(100)
AB=10
The distance between point A and point B is 10 units.

Extra

The Distance Formula and the Pythagorean Theorem
The Distance Formula is related to the Pythagorean Theorem. Let's consider two points in a coordinate plane. We can draw a right triangle with the hypotenuse that is the segment AB.
triangle
Now, the difference between the x-coordinates of the points is the length of one of the legs of the triangle. The length of the other leg is the difference between the y-coordinates. Therefore, the lengths of the legs are x_2-x_1 and y_2-y_1. Let's write the equation for this triangle based on the Pythagorean Theorem. AB^2=( x_2-x_1)^2+( y_2-y_1)^2 ⇕ AB=sqrt((x_2-x_1)^2+(y_2-y_1)^2) Notice that, when solving for AB, we only need to consider the principal root because AB must be positive.