Write the equation of a circle whose center is (-4,7) and has a radius of 4? Write the equation of a circle whose center is (6,5) and has a radius of 3 square root of 5?

1 Answer
Jim G.
Apr 25, 2018

#(x+4)^2+(y-7)^2=16" and "(x-6)^2+(y-5)^2=45#

Explanation:

#"the equation of a circle in "color(blue)"standard form"# is.

#"color(red)(bar(ul(|color(white)(2/2)color(black)((x-a)^2+(y-b)^2=r^2)color(white)(2/2)|)))#

#"where "(a,b)" are the coordinates of the centre and r"#
#"is the radius"#

#"centre "(-4,7)" and "r=4#

#(x-(-4))^2+(y-7)^2=4^2#

#rArr(x+4)^2+(y-7)^2=16larrcolor(red)"equation of circle"#

#"centre "(6,5)" and "r=3sqrt5#

#(x-6)^2+(y-5)^2=(3sqrt5)^2#

#rArr(x-6)^2+(y-5)^2=45larrcolor(red)"equation of circle"#

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