Derivatives of Trigonometric Functions: Solving for dy/dx and d²y/dx²

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In summary, the 1st derivative represents the rate of change of a function at a specific point and is used in various fields to analyze and predict changes over time. The 2nd derivative measures how quickly the slope of a curve is changing and can be used to find critical points and the inflection point of a curve.
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Homework Statement


If x = cos(3t) and y = (sin(3t))² find dy/dx and d²y/dx².

Homework Equations


d/dx cosx = -sinx
d/dx sinx = cosx

The Attempt at a Solution


dx/dt = -3sin3t
dy/dt = 6sin3tcos3t

Not sure what to do now.
 
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  • #2
(dy/dt)/(dx/dt)=dy/dx, right?
 
  • #3
Yes, thank you. After I posted I wondered whether you could do that or not (a little unfamiliar with Leibniz notation) but it makes sense now thank you.
 

Related to Derivatives of Trigonometric Functions: Solving for dy/dx and d²y/dx²

1. What is the definition of the 1st derivative?

The 1st derivative, also known as the slope of a curve, represents the rate of change of a function at a specific point. It is calculated as the change in output divided by the change in input.

2. How is the 1st derivative used in real life?

The 1st derivative is used in various fields such as physics, economics, and engineering to analyze and predict changes in quantities over time. For example, it can be used to calculate the velocity of an object or the rate of change of a company's profits.

3. What is the relationship between the 1st and 2nd derivative?

The 2nd derivative is the rate of change of the 1st derivative. In other words, it measures how quickly the slope of a curve is changing. The 2nd derivative can provide information about the concavity of a curve and whether it is increasing or decreasing.

4. How is the 2nd derivative used to find critical points?

Critical points are points on a function where the derivative is equal to zero or does not exist. To find these points, we use the 2nd derivative test, which involves looking at the sign of the 2nd derivative at a given point. If the 2nd derivative is positive, the point is a minimum, and if it is negative, the point is a maximum.

5. Can the 1st and 2nd derivative be used to find the inflection point of a curve?

Yes, the 1st and 2nd derivative can be used to find the inflection point of a curve. The inflection point is where the concavity of a curve changes, and it can be found by setting the 2nd derivative equal to zero and solving for the input value.

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