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Course: Staging content lifeboat > Unit 10

Lesson 2: Conic sections
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Staging content lifeboat
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Conic sections
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DEPRECATED Pythagorean theorem and the equation of a circle

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Problem

Circle O has a center at (h,k) and a radius of 20.
To derive the equation of this circle, we will use the Pythagorean theorem.
First, we pick any point on the circle and call it A, with coordinates (x,y). We create a right triangle with hypotenuse OA― and vertex at right angle B.
Use the Pythagorean theorem to find the equation of the circle.
What is the length of OB― ?
What is the length of AB― ?
Write the equation of the circle.