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1. consider the circle with center (0,0) that passes through the point (-4,2)

find the radius of the circle

2.considere the circle with equation (x-1)^2+(y+7)^2=29

what is the center of the circle?

give ur answer in (a,b) form

 May 19, 2020
 #1
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1)  To find the radius of the circle, we need to find the distance from (0,0) to (-4,,2).

      Distance formula:  d  =  sqrt( (x2 - x1)2 + (y2 - y1)2 )

                                        =  sqrt( (-4 - 0)2 + (2 - 0)2 )

                                        =  sqrt( 16 + 4)

                                        =  sqrt( 20 )  

                                        =  sqrt( 4 · 5 )

                                        =  sqrt( 4 ) · sqrt( 5 )

                                        =  2 · sqrt( 5 )

 

2)  If the equation for a circle is in this form:  (x - h)2 + (y - k)2  =  r2

     then the center is at (h, k) and the radius is r.

 

     (x - 1)2 + (y + 7)2  =  29     --->     center  =  (1,-7)     radius  =  sqrt( 29 )

 May 19, 2020
 #2
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thank you!

xxJenny1213xx  May 19, 2020

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