Grade 11 · Geometry & measurement

Conic sections practice

Conic sections is a grade 11 math skill aligned to Common Core standard HSG.GPE.A.3: derive the equations of ellipses and hyperbolas given the foci. Below are 8 practice questions with answers and step-by-step explanations, drawn from the 20 conic sections problems our math games drill.

CCSS HSG.GPE.A.320 questions in the bank
Sample questions

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Question 1easy

What is the radius of the circle (x1)2+(y5)2=36(x - 1)^{2} + (y - 5)^{2} = 36?

The form (xh)2+(yk)2=r2(x - h)^{2} + (y - k)^{2} = r^{2} gives r2=36r^{2} = 36, so r=36=6r = \sqrt{36} = 6.

Question 2easy

For the ellipse x225+y29=1\dfrac{x^{2}}{25} + \dfrac{y^{2}}{9} = 1, what is the length of the semi-minor axis?

The smaller denominator is b2=9b^{2} = 9, so the semi-minor axis has length b=9=3b = \sqrt{9} = 3.

Question 3easy

The hyperbola x216y29=1\dfrac{x^{2}}{16} - \dfrac{y^{2}}{9} = 1 has a vertex on the positive x-axis. What is the x-coordinate of that vertex?

Set y=0y = 0: then x2=16x^{2} = 16, so the vertices are (±4,0)(\pm 4, 0) and the positive x-coordinate is 44.

Question 4easy

Identify the conic: x29+y24=1\dfrac{x^{2}}{9} + \dfrac{y^{2}}{4} = 1.

Both variables are squared with positive coefficients and different denominators: this is an ellipse.

Question 5easy

The graph of y=(x3)2+5y = (x - 3)^{2} + 5 is a parabola. What is the x-coordinate of its vertex?

Vertex form y=(xh)2+ky = (x - h)^{2} + k has vertex (h,k)(h, k), so the vertex is (3,5)(3, 5) and the x-coordinate is 33.

Question 6easy

The ellipse x225+y29=1\dfrac{x^{2}}{25} + \dfrac{y^{2}}{9} = 1 crosses the positive x-axis at one point. What is the x-coordinate of that point?

Set y=0y = 0: then x2=25x^{2} = 25, and the positive solution is x=5x = 5.

Question 7easy

The hyperbola y225x24=1\dfrac{y^{2}}{25} - \dfrac{x^{2}}{4} = 1 opens up and down. What is the y-coordinate of the vertex on the positive y-axis?

Set x=0x = 0: then y2=25y^{2} = 25, so the vertices are (0,±5)(0, \pm 5) and the positive y-coordinate is 55.

Question 8easy

Identify the conic: x216y29=1\dfrac{x^{2}}{16} - \dfrac{y^{2}}{9} = 1.

One squared term is subtracted from the other: this is a hyperbola.

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