# Graphs and Equations of Circles Book: Math 3 (Green Book) Section: 5.2.

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Graphs and Equations of Circles Book: Math 3 (Green Book) Section: 5.2

Standard Equation of a Circle What do you think we need to write an equation of a circle? Radius Center Point on a Circle

Lets See What We Know The point (6, 2) lies on a circle whose center is at the origin. Find the radius. What formula do we need to use in order to find the radius? DISTANCE FORMULA!!!!!!!

Lets See What We Know The point (-2, -2) lies on a circle whose center is at (4, -5). Find the radius.

Lets Make Some Observations Whats the Radius? Where is the center? Here is the equation, how is it related to the circle?

Lets Make Some Observations Whats the Radius? Where is the center? Here is the equation, how is it related to the circle?

So we have determined… Let the center of a circle be the point (h,k) and the radius be r From our observations we have determined that the standard equation of a circle is:

Write the Equation of the Circle

Graph the Circle

Write the Equation of the Circle Center: originRadius: 5 Center: (4, -2)Radius:

Homework GREEN BOOK Pg. 182 #1 – 22 WS

9. 10. 11. From the worksheet

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