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Problem 8 - Entrance Test

Convert the rectangular equation (x² + y²)^(3/2) = 2xy to its polar form.

Correct: A

We use the standard conversions between rectangular and polar coordinates: x = rcos(θ) y = rsin(θ) x² + y² = r² Substitute these into the given rectangular equation: (x² + y²)^(3/2) = 2xy (r²)^(3/2) = 2(rcos(θ))(rsin(θ)) r^3 = 2r²cos(θ)sin(θ) We know that 2sin(θ)cos(θ) = sin(2θ). So: r^3 = r²sin(2θ) To simplify, divide both sides by r². We must consider the case where r=0 separately. If r=0, then 0=0, so the pole is included. Dividing by r² assumes r ≠ 0, but the resulting equation usually covers the pole anyway. r = sin(2θ) The final answer is A.