Math Problem Statement

find dy/dx and the slope of the curve at the indicated point. Which of the following gives dy/dx for the parametric curve x ! 3 sin t, y ! 2 cos t?

Solution

To find dydx\frac{dy}{dx} for the parametric curve defined by: x=3sintandy=2costx = 3 \sin t \quad \text{and} \quad y = 2 \cos t

we need to calculate the derivatives dxdt\frac{dx}{dt} and dydt\frac{dy}{dt} with respect to tt and then use the formula: dydx=dydtdxdt.\frac{dy}{dx} = \frac{\frac{dy}{dt}}{\frac{dx}{dt}}.

Step 1: Differentiate xx and yy with respect to tt

  1. Differentiate x=3sintx = 3 \sin t: dxdt=3cost.\frac{dx}{dt} = 3 \cos t.

  2. Differentiate y=2costy = 2 \cos t: dydt=2sint.\frac{dy}{dt} = -2 \sin t.

Step 2: Substitute into dydx\frac{dy}{dx}

Now, we substitute these derivatives into the formula: dydx=dydtdxdt=2sint3cost=23tant.\frac{dy}{dx} = \frac{\frac{dy}{dt}}{\frac{dx}{dt}} = \frac{-2 \sin t}{3 \cos t} = -\frac{2}{3} \tan t.

Slope of the Curve at the Indicated Point

To find the slope at a specific point, substitute the value of tt that corresponds to that point into 23tant-\frac{2}{3} \tan t. If you provide the specific point, I can calculate the exact slope for you.

Would you like details on the specific point to continue?


Here are five follow-up questions to extend this information:

  1. How do we interpret the result of dydx\frac{dy}{dx} geometrically on a parametric curve?
  2. How would we proceed if the parametric equations were given in terms of a different parameter?
  3. What if we wanted to find d2ydx2\frac{d^2y}{dx^2} for this parametric curve?
  4. How does the approach differ if the curve was defined implicitly instead of parametrically?
  5. What is the effect on dydx\frac{dy}{dx} if the coefficients in x=asintx = a \sin t and y=bcosty = b \cos t were different?

Tip: Always check for periodic points on parametric curves like sine and cosine to simplify calculations for specific values.

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Math Problem Analysis

Mathematical Concepts

Calculus
Parametric Equations
Differentiation

Formulas

dy/dx = (dy/dt) / (dx/dt)
dx/dt for x = 3 sin t is 3 cos t
dy/dt for y = 2 cos t is -2 sin t

Theorems

Parametric Differentiation

Suitable Grade Level

Grade 11-12