Q. A circle in the xy-plane has the equation 4x2+4y2−24x=28. What is the diameter of the circle?
Rewrite equation in standard form: Rewrite the equation of the circle in standard form.The given equation is 4x2+4y2−24x=28. To rewrite it in standard form, we need to complete the square for the x-terms and move the constant term to the other side.First, factor out the 4 from the x-terms and y-terms:4(x2+y2−6x)=28Now, divide both sides by 4 to simplify:x2+y2−6x=7Next, complete the square for the x-terms by adding (26)2=9 to both sides:x2−6x+9+y2=7+9Now, the equation becomes:(x−3)2+y2=16
Identify the radius: Identify the radius of the circle.The standard form of a circle's equation is (x−h)2+(y−k)2=r2, where (h,k) is the center of the circle and r is the radius.Comparing our equation (x−3)2+y2=16 with the standard form, we can see that r2=16.To find the radius r, we take the square root of both sides:r=16r=4
Calculate the diameter: Calculate the diameter of the circle.The diameter of a circle is twice the radius.Diameter = 2×radiusDiameter = 2×4Diameter = 8
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