The equation of an ellipse is given below.3(x−5)2+6(y−7)2=1What are the foci of this ellipse?Choose 1 answer:(A) (5,7+3) and (5,7−3)(B) (−5,−7+3) and (−5,−7−3)(C) (−5+3,−7) and (−5−3,−7)(D) (5+3,7) and (5−3,7)
Q. The equation of an ellipse is given below.3(x−5)2+6(y−7)2=1What are the foci of this ellipse?Choose 1 answer:(A) (5,7+3) and (5,7−3)(B) (−5,−7+3) and (−5,−7−3)(C) (−5+3,−7) and (−5−3,−7)(D) (5+3,7) and (5−3,7)
Identify Center and Axes: Identify the center and lengths of the semi-major and semi-minor axes.The given equation of the ellipse is 3(x−5)2+6(y−7)2=1. The standard form of an ellipse is a2(x−h)2+b2(y−k)2=1, where (h,k) is the center of the ellipse, a is the length of the semi-major axis, and b is the length of the semi-minor axis. For our ellipse, h=5, k=7, a2=3, and b2=6. Therefore, a=3 and a2(x−h)2+b2(y−k)2=10.
Determine Major Axis: Determine which axis is the major axis.Since a^2 < b^2, the major axis is along the y-direction. This means that the foci will be found by moving up and down from the center along the y-axis.
Calculate Distance to Foci: Calculate the distance from the center to the foci. The distance c from the center to each focus is given by the formula c2=b2−a2. Plugging in the values we have c2=6−3=3. Therefore, c=3.
Find Foci Coordinates: Find the coordinates of the foci.The foci are located at (h,k±c) since the major axis is vertical. Substituting the values we have, the foci are at (5,7±3).
Choose Correct Answer: Choose the correct answer.The correct answer is (A) (5,7+3) and (5,7−3), since these are the coordinates we found for the foci.
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