The equation of an ellipse is given below.100(x+9)2+64y2=1What are the foci of this ellipse?Choose 1 answer:(A) (−9,−3) and (−9,3)(B) (−9,−6) and (−9,6)(C) (−15,0) and (−3,0)(D) (−12,0) and (−6,0)
Q. The equation of an ellipse is given below.100(x+9)2+64y2=1What are the foci of this ellipse?Choose 1 answer:(A) (−9,−3) and (−9,3)(B) (−9,−6) and (−9,6)(C) (−15,0) and (−3,0)(D) (−12,0) and (−6,0)
Identify center and lengths: Identify the center and lengths of the major and minor axes.The given equation of the ellipse is 100(x+9)2+64y2=1. This is in the standard form of an ellipse equation, which is a2(x−h)2+b2(y−k)2=1, where (h,k) is the center of the ellipse, a is the semi-major axis length, and b is the semi-minor axis length. For our ellipse, h=−9, k=0, a2=100, and b2=64. Therefore, a=10 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 x-axis, and the minor axis is along the y-axis. This means that the foci will be located along the x-axis, at a distance of c from the center, where c is found using the formula c=a2−b2.
Calculate distance to foci: Calculate the distance c from the center to each focus. Using the formula c=a2−b2, we find c=100−64=36=6. This means the foci are located 6 units to the left and right of the center along the x-axis.
Find coordinates of foci: Find the coordinates of the foci. The center of the ellipse is at (−9,0). The foci are located at (−9−c,0) and (−9+c,0). Substituting the value of c, we get the foci at (−9−6,0) and (−9+6,0), which simplifies to (−15,0) and (−3,0).
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