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Calculating the Distance Between Two Points

Now let's explore the circle on the coordinate plane.
When a circle is positioned on the coordinate plane, the distance between the centre and a point on the circle can be calculated. This distance is called the radius of the circle.
You calculate this distance using the Distance Formula.
The distance formula is:

d =

Ö
_________________
(x2 - x1)2 + (y2 - y1)2

= [(x2 - x1)2 + (y2 - y1)2]½

where d is the distance between any two points (x1, y1) and (x2, y2) in the plane.
How is the Distance Formula related to the Pythagorean Theorem?
Follow the steps in the questions below to calculate the radius of a circle centred at P that goes through the point Q, and then construct this circle.

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