How do I graph the function f(x) = cos^2(x) - sin^2(x) over the interval [-2pi,2pi] and use 100 points in the domain?

graph

[James Tursa]

What have you done so far? What specific problems are you having with your code?

[Mahammed Ali]

I dont know how to type cos^2(x)- sin^2(x) into matlab. I think it is cos(x).^2 - sin(x).^2. Also I know the interval is typed out [-2*pi, 2*pi} but I dont understand what the question means by saying using 100 points in the domain

[John D'Errico]

When you have a problem that is too complex for you to solve, break it down into pieces. Then solve each piece, one at a time.

1. Can you generate 100 points, equally spaced from -2*pi to 2*pi?

2. Evaluate the function at those points?

3. Plot the result, y as a function of x, at the points you have just evaluated your function.

This is a small problem, tiny even. But the general rule still applies: Eat a programming elephant one byte at a time.

MAKE AN EFFORT. You will learn by doing.

[Janaki]

Plot the function f(x) = sin^2(x)cos(2x) and its derivative, both on the same plot, for 0 lessthanorequalto x lessthanorequalto 2pi. Plot the function with a solid line, and the derivative with a dashed line. Add a legend and label the axes.

[Image Analyst]

@Janaki, This looks like a homework problem. Please start your own question for this homework if you can't figure out how to say

x = linspace(0, 2 * pi, 1000);
f = sin(x).^2 * cos(2 * x);
plot(f, x, 'b-');

It's really quite simple so I'm guessing you never took the MATLAB onramp training. Please invest 2 hours of your time here so that you don't need to ask about every simple thing like this: MATLAB Academy - Free 2 hour training

If you have any questions ask your instructor or read the link below to get started:

How do I get help on homework questions on MATLAB Answers? - MATLAB Answers - MATLAB Central

Obviously we can't give you the full solution because you're not allowed to turn in our code as your own.

For the derivative, I'd just compute the formula analytically using techniques: https://web.iit.edu/sites/web/files/departments/academic-affairs/academic-resource-center/pdfs/product_quotient_rule.pdf then plot it with plot.

Answer 1

[Image Analyst]

Your formula

y = cos(x).^2 - sin(x).^2

is correct. What you're missing is how to create x. Hint: use the linspace() function.

Answer 2

[Hina Shaheen]

f(x)= cos^2(x)-sin^2(x) over the interval -2pie, 2pie

[Image Analyst]

Hina, I already answered it above in my Answer. Perhaps you overlooked it. Here is what you would have gotten:

x = linspace(-2*pi, 2*pi, 100);
fx = cos(x) .^ 2 - sin(x) .^ 2;
plot(x, fx, 'b-', 'LineWidth', 2);
grid on;
xlabel('x', 'FontSize', 20);
ylabel('f(x)', 'FontSize', 20);

Answer 3

[mostafa mohamad]

t=1:5

y=2*cos(2*pi*1400*t

)

[Image Analyst]

Not sure how this is an answer to plotting f(x) = cos^2(x) - sin^2(x) over the interval [-2pi,2pi].

Like I said, the solution is

x = linspace(-2*pi, 2*pi, 100);
fx = cos(x) .^ 2 - sin(x) .^ 2;
plot(x, fx, 'b-', 'LineWidth', 2);
grid on;
xlabel('x', 'FontSize', 20);
ylabel('f(x)', 'FontSize', 20);