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The polar equation ʳ²(2+3coˢ²(θ))=64 represents,

(A) a parabola
(B) a hyperbola
(C) an ellipse
(D) a straight line
(E) a cirele with center (1,0) and radius 4
(F) a circle with center (0,1) and radius 4

User Nohemi
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1 Answer

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Final answer:

The given polar equation represents an ellipse, not a parabola, as it can be rewritten in Cartesian form to fit the definition of an ellipse where the sum of distances from any point on the curve to the foci is constant.

Step-by-step explanation:

The given polar equation r²(2+3cos²(θ))=64 can be analyzed to determine the shape of the curve it represents. It is a conic section, and in polar coordinates, conic sections have the general form r(1+εcos(φ)), where ε is the eccentricity. If ε=1, the conic is a parabola. However, in this equation, we do not have this form, so it's unlikely to represent a parabola. To further analyze the given equation, we expand it to r² + 3r²cos²(θ) = 64. Now we need to see if we can rewrite this in Cartesian coordinates.

Using the polar to Cartesian conversion identities x = r cos(θ) and y = r sin(θ), we attempt to transform the equation. Given that r² = x² + y², we substitute this into the equation and get x² + y² + 3x² = 64, which simplifies to 4x² + y² = 64. This equation does not have the typical form of x = ay² + by + c, which defines a parabola. Instead, it's an ellipse, specifically when rearranged to x²/16 + y²/64 = 1, where the sum of the distances from any point on the curve to the foci is constant. This matches the definition of an ellipse described in your study material.

User Robert Atkins
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