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MATH 01131 · Calculus II

MATH 01131 · Parametric & polar (often)

Polar area / graphing r(θ)

Definition

Polar: x=r cosθ, y=r sinθ. Area of a polar region: (1/2)∫ₐᵇ [r(θ)]² dθ. Graph by plotting key θ and knowing rose/cardioid/limaçon families.

Read this

r<0 means going opposite the ray θ (depending on convention taught).

Find intersections carefully — same point can have multiple (r,θ) pairs.

Convert to Cartesian when recognition helps (r²=x²+y²).

Drill with flashcards

Flip through these until you can say the answer before revealing it.

Flashcards · 1 / 3

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Try this

Attempt each problem first, then open the worked solution.

  1. 1.Area of one petal of r=sin(2θ).