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The general form of the equation of a circle is 7x2 + 7y2 − 28x + 42y − 35 = 0. The equation of this circle in standard form is . The center of the circle is at the point , and its radius is units. |
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Answer» The standard equation for a circle is : (x - h)² + (y - K) ² = r² With center (h, k) and radius r Lets write the given equation in this form. COLLECT the LIKE terms together : 7x² - 28x + 7y² + 42Y = 35 Dividing through by 7 we have : x² - 4x + y² + 6y = 5 Completing SQUARES we have : x² - 4x +(4/2)² + y² + 6y +(6/2)² = 5 + (4/2)² + (6/2)² (x - 2)² + (y + 3)² = 5 + 4 + 9 (x - 2)² + (y + 3)² = 18 r² = 18 r = 4.243 Center : (2, - 3) |
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