Circles, when graphed on the coordinate plane, have an equation of x2 + y2 = r2 where r is the radius (standard form) when the center of the circle is the origin. When the center of the circle is (h, k) and the radius is of length r, the equation of a circle (standard form) is (x - h)2 + (y - k)2 = r2.
Example: 1. Problem: Find the center and radius of (x - 2)sq + (y + 3)sq = 16. Then graph the circle.
Solution: Rewrite the equation in standard form. (x - 2)sq + [y - (-3)]sq = 4sq
The center is (2, -3) and the radius is 4. The graph is easy to draw, especially if you use a compass. The figure below is the graph of the solution.http://library.thinkquest.org/20991/...g2_circles.gif
here are my questions:
~How did they get -2 and -3 as the center point of the circle?
~How come the formula change from x2+y2= r2 to (x-h)2 + (y-k)2 = R2?
~Sorry i'm kind of dumb on these things. =) thank you
your equation of circle is
that will be one with center in (0,0)
but equation of sifted circle is
so to see where your center is just :
so center is in (a,b) :D
both formulas are the same, just in first one ( with center circle) you have that your a=0 and b=0 meaning that it's not shifted ...
P.S. your center up there is not as you write (-2,-3) it's (2,-3) but that just typo i think :D
Originally Posted by Gordon
@Ye, your the best bro.
@Archie, almost got me confuse but i still got it.