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Which of the following is the derivative (dy)/(dx) for the plane curve defined by the equations x(t)=(1)/(2)sin 2t, y(t)=2cos 2t, and 0 <= t <= 2pi ?
Select the correct answer below:
(A) 4cot 2t
(B) tan 4t
(C) -tan 4t
(D) -4tan 2t

Which of the following is the derivative dydx \frac{d y}{d x} for the plane curve defined by the equations x(t)=12sin2t x(t)=\frac{1}{2} \sin 2 t , y(t)=2cos2t y(t)=2 \cos 2 t , and 0t2π 0 \leq t \leq 2 \pi ?\newlineSelect the correct answer below:\newline(A) 4cot2t 4 \cot 2 t \newline(B) tan4t \tan 4 t \newline(C) tan4t -\tan 4 t \newline(D) 4tan2t -4 \tan 2 t

Full solution

Q. Which of the following is the derivative dydx \frac{d y}{d x} for the plane curve defined by the equations x(t)=12sin2t x(t)=\frac{1}{2} \sin 2 t , y(t)=2cos2t y(t)=2 \cos 2 t , and 0t2π 0 \leq t \leq 2 \pi ?\newlineSelect the correct answer below:\newline(A) 4cot2t 4 \cot 2 t \newline(B) tan4t \tan 4 t \newline(C) tan4t -\tan 4 t \newline(D) 4tan2t -4 \tan 2 t
  1. Find Derivative Process: To find the derivative dydx\frac{dy}{dx}, we need to find dydt\frac{dy}{dt} and dxdt\frac{dx}{dt} first and then divide dydt\frac{dy}{dt} by dxdt\frac{dx}{dt}.
  2. Calculate dxdt\frac{dx}{dt}: Calculate dxdt\frac{dx}{dt}:dxdt=ddt[12sin(2t)]=12ddt[sin(2t)]=122cos(2t)=cos(2t)\frac{dx}{dt} = \frac{d}{dt} \left[\frac{1}{2}\sin(2t)\right] = \frac{1}{2} \cdot \frac{d}{dt} [\sin(2t)] = \frac{1}{2} \cdot 2\cos(2t) = \cos(2t)
  3. Calculate dydt\frac{dy}{dt}: Calculate dydt\frac{dy}{dt}:dydt=ddt[2cos(2t)]=2×ddt[cos(2t)]=2×(2sin(2t))=4sin(2t)\frac{dy}{dt} = \frac{d}{dt} [2\cos(2t)] = -2 \times \frac{d}{dt} [\cos(2t)] = -2 \times (-2\sin(2t)) = 4\sin(2t)
  4. Find (dydx):</b>Now,find$(dydx)(\frac{dy}{dx}):</b> Now, find \$(\frac{dy}{dx}) by dividing dydt\frac{dy}{dt} by dxdt:\frac{dx}{dt}:\newline(\frac{dy}{dx}) = \frac{(\frac{dy}{dt})}{(\frac{dx}{dt})} = \frac{(\(4\)\sin(\(2\)t))}{(\cos(\(2\)t))} = \(4\tan(22t)
  5. Check Answer Choices: However, we need to check the answer choices to see which one matches our result. The correct answer should be in terms of tt and should match the form of the derivative we found.
  6. Correcting Mistake: The answer choices are:\newlineA) 4cot2t4\cot 2t\newlineB) tan4t\tan 4t\newlineC) tan4t-\tan 4t\newlineD) 4tan2t-4\tan 2t\newlineOur result is 4tan(2t)4\tan(2t), which is not listed. We need to check if we made a mistake or if there is a trigonometric identity that can transform our result into one of the given options.
  7. Correcting Mistake: The answer choices are:\newlineA) 4cot2t4\cot 2t\newlineB) tan4t\tan 4t\newlineC) tan4t-\tan 4t\newlineD) 4tan2t-4\tan 2t\newlineOur result is 4tan(2t)4\tan(2t), which is not listed. We need to check if we made a mistake or if there is a trigonometric identity that can transform our result into one of the given options.Upon reviewing, we realize that we made a mistake in our calculation. The correct derivative should be in terms of 2t2t, not 4t4t. Therefore, the correct answer should be 4tan(2t)-4\tan(2t) because the derivative of yy with respect to tt is negative, and we missed the negative sign in our previous step.

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