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AP® Calculus AB-BC

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Moderate

Derivatives and Polar Equations

APCALC-IFKSPG

Which of these polar equations has a tangent line with a negative slope when $\theta=\cfrac{2\pi}{3}$ and is also concave up at that point?

A

$r=2\sin{\theta}$

B

$r=2+3\cos{\theta}$

C

$r=4\sin{3\theta}$

D

$r=4\cos{3\theta}$