For the equation \( x^{2}+y^{2}-2 x-4 y-20=0 \), do the following. (a) Find the center \( (h, k) \) and radius \( r \) of the circle. (b) Graph the circle. (c) Find the intercepts, if any. (a) The center is (Type an ordered pair.)
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Bonus Knowledge
To find the center and radius of the circle represented by the equation \( x^{2}+y^{2}-2 x-4 y-20=0 \), we can rewrite it in the standard form. 1. First, we rearrange the equation: \[ x^{2} - 2x + y^{2} - 4y = 20. \] 2. Next, we complete the square for \( x \) and \( y \). - For \( x^{2} - 2x \): - Take half of -2, square it: \((-1)^{2}=1\). - Add and subtract 1: \( (x^2 - 2x + 1) - 1 = (x - 1)^{2} - 1 \). - For \( y^{2} - 4y \): - Take half of -4, square it: \((-2)^{2}=4\). - Add and subtract 4: \( (y^2 - 4y + 4) - 4 = (y - 2)^{2} - 4 \). 3. Incorporating these into the equation gives: \[ (x - 1)^{2} - 1 + (y - 2)^{2} - 4 = 20. \] 4. Simplifying results in: \[ (x - 1)^{2} + (y - 2)^{2} = 25. \] Now we can identify the center and radius: - Center \((h, k) = (1, 2)\) - Radius \(r = 5\) (since \( r^2 = 25\)). (a) The center is \( (1, 2) \).