MHB Area B/w Curves: y=(secx)^2/4 & 4(cosx)^2

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The discussion focuses on finding the area between three pairs of curves: y=(secx)^2/4 and y=4(cosx)^2, y=e^x and y=e^-4x with x=ln4, and y=5cosx and y=5cos(2x) over the interval [0, π]. The area between two curves is calculated using the integral of the difference between the upper and lower functions over the specified interval. Participants are encouraged to show their work to facilitate better assistance. The forum emphasizes the importance of limiting questions per thread to enhance clarity and learning. Overall, the thread aims to assist users in applying integral calculus to determine areas between curves effectively.
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Determine the area between:

1.) y=((secx)^2)/4 and y=4(cosx)^2

2.) y=e^x , y=e^-4x , and x=ln4

3.) y=5cosx and y=5cos(2x) for 0≤x≤pi
 
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brickair said:
Determine the area between:

1.) y=((secx)^2)/4 and y=4(cosx)^2

2.) y=e^x , y=e^-4x , and x=ln4

3.) y=5cosx and y=5cos(2x) for 0≤x≤pi

The area between $y=f(x)$ and $y=g(x)$ on the interval $[a,b]$, when $f(x) \geq g(x)$ is euqal to $\displaystyle{\int_a^bf(x)-g(x) dx}$.

Can you apply this in your case?
 
brickair said:
Determine the area between:

1.) y=((secx)^2)/4 and y=4(cosx)^2

2.) y=e^x , y=e^-4x , and x=ln4

3.) y=5cosx and y=5cos(2x) for 0≤x≤pi

Hello and welcome to MHB!

Just for future reference, we ask that you:

a) Post no more than two questions per thread in your initial post. Follow-up questions are fine, but if you have a new question, please begin a new thread.

b) Show what you have tried, as this gives our helpers a better idea where you are stuck and how best to help. Our goal here is to maximize the learning for the person asking the question by getting them involved in the solution process.
 
There are probably loads of proofs of this online, but I do not want to cheat. Here is my attempt: Convexity says that $$f(\lambda a + (1-\lambda)b) \leq \lambda f(a) + (1-\lambda) f(b)$$ $$f(b + \lambda(a-b)) \leq f(b) + \lambda (f(a) - f(b))$$ We know from the intermediate value theorem that there exists a ##c \in (b,a)## such that $$\frac{f(a) - f(b)}{a-b} = f'(c).$$ Hence $$f(b + \lambda(a-b)) \leq f(b) + \lambda (a - b) f'(c))$$ $$\frac{f(b + \lambda(a-b)) - f(b)}{\lambda(a-b)}...

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