Differentiating a trig function to the power of 2

In summary, to verify a maximum using a double derivative, it is necessary to differentiate -5sin^2(x) twice. The first derivative would be -10cos(x)sin(x), using the chain rule and substituting u=sin(x). The second derivative would be -10cos(x), and in order to find the maximum value, it is necessary to differentiate once more.
  • #1
chung963
3
0

Homework Statement


I'm doing a optimisation question and I get to a point where I have to verify a maximum using a double derivative and I need to differentiate -5sin^2(x)

Homework Equations


-5sin^2(x)


The Attempt at a Solution


-10cos(x)sin(x) I am not sure if the answer is positive or negative.
 
Physics news on Phys.org
  • #2
-10cos(x)sin(x) would be your first derivative .
 
  • #3
You are using the chain rule: [itex]-5sin^2(x)[/itex] can be written as [itex]-5u^2[/itex] with [itex]u= sin(x)[/itex]. The derivative of [itex]-5u^2[/itex], with respect to u, is -10u and the derivative of [itex]u= sin(x)[/itex] with respect to x is [itex]cos(x)[/itex]. Multiply those together.
 
  • #4
it is negative and in order to find maximum value you have to differentiate once more
 

Related to Differentiating a trig function to the power of 2

What is the general formula for differentiating a trigonometric function to the power of 2?

The general formula for differentiating a trigonometric function to the power of 2 is:
d/dx(sin^2(x)) = 2sin(x)cos(x)

Can the power of 2 be applied to any trigonometric function?

Yes, the power of 2 can be applied to any trigonometric function, such as cosine, tangent, or secant.

What is the difference between differentiating a trigonometric function to the power of 2 and a regular trigonometric function?

The difference is that when differentiating a trigonometric function to the power of 2, the power rule must be applied. This means that the exponent is brought down in front and the original function is raised to the power of one less. For example, d/dx(sin^2(x)) = 2sin(x)cos(x), while d/dx(sin(x)) = cos(x).

Can the power of 2 be applied multiple times to a trigonometric function?

Yes, the power of 2 can be applied multiple times to a trigonometric function. For example, d/dx(sin^4(x)) = 4sin^3(x)cos(x).

Are there any special cases when differentiating a trigonometric function to the power of 2?

Yes, there are a few special cases when differentiating a trigonometric function to the power of 2. One example is when differentiating cotangent squared, which results in a negative cosecant squared. Another special case is when differentiating secant squared, which results in a tangent multiplied by the secant squared.

Similar threads

  • Calculus and Beyond Homework Help
Replies
7
Views
393
  • Calculus and Beyond Homework Help
Replies
2
Views
183
Replies
4
Views
977
  • Calculus and Beyond Homework Help
Replies
1
Views
309
  • Calculus and Beyond Homework Help
Replies
1
Views
365
  • Calculus and Beyond Homework Help
Replies
10
Views
975
  • Calculus and Beyond Homework Help
Replies
5
Views
594
  • Calculus and Beyond Homework Help
Replies
18
Views
1K
  • Calculus and Beyond Homework Help
Replies
6
Views
1K
  • Calculus and Beyond Homework Help
Replies
6
Views
1K
Back
Top