Precalculus : Determine the Equation of a Circle in Standard Form
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Example Question #31 : Determine The Equation Of A Circle In Standard Form
If each mark on the graph represents 
Since the circle is centered at 
Given the circle has a radius of 
We then plug in 
Example Question #31 : Determine The Equation Of A Circle In Standard Form
Which point is NOT on the circle defined by 
The point 
We can test to see if the other points are actually on the circle by plugging in their x and y values into the equation. For example, to verify that
Example Question #32 : Determine The Equation Of A Circle In Standard Form
Which best describes the point 
The point is inside the circle
The point is outside the circle
The point has no relationship with the circle
The point is on the circle
The point is the focus of the circle
The point is outside the circle
To quickly figure this out, we can plug in 5 for x and -2 for y and see what happens:
Since the value is greater than 9, this point is outside the radius of this circle.
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