Y = X . COS(X) . SIN(X)

How would I go about plotting the following equation?

Y = X .* cos(X) .* sin(X);

[Sumanth Reddy Allala]

2. Identify the missing code to find f(7) and f(8) for the function

f(x) = x?cos(x + 1),

MATLAB code

x=linspace(0,3);

f(x)=x^2*cosx+1

f(7)

f(8)

[Image Analyst]

Sumanth, I think you meant to post a new question rather than a comment here. I don't see how this would in any way be a comment or question for Albert. Please start your own question after you read this link.

[Shahid]

sinx(1+cosx) is maximum

[Shahid]

sinx(1+cosx) is maximum when x=pi

[Image Analyst]

@Shahid , I think you meant to post a new question rather than a comment here. I don't see how this would in any way be a comment or question for Albert. Please start your own question after you read this link.

Answer 1

[Image Analyst]

You didn't say over what range to plot x, so I'm going to assume it's from -20 to 20. Adapt as needed:

% Choose a range for x and use 500 points.
X = linspace(-20, 20, 500);
% Create Y
Y = X .* cos(X) .* sin(X);
% Plot the function.
plot(X, Y, 'b-', 'LineWidth', 2);
grid on;
xlabel('X', 'FontSize', 15);
ylabel('Y', 'FontSize', 15);
title('Y = X .* cos(X) .* sin(X)', 'FontSize', 15);
axis equal;
% Make a black line at the x and y axes
line(xlim, [0, 0], 'Color', 'k', 'LineWidth', 2);
line([0, 0], ylim, 'Color', 'k', 'LineWidth', 2);

Answer 2

[madhan ravi]

syms x  %SYMBOLIC TOOLBOX

Y = x .* cos(x) .* sin(x)
fplot(Y)

or

x= linspace(-100,100,1000)

y=x .* cos(x) .* sin(x)

plot(x,y)

[madhan ravi]

See attached screenshot of the graph you need

[Albert Barajas]

is the symbolic toolbox an add on I need to add ? I am currently running the trial version of matlab and it says "syms requires symbolic math toolbox"

[madhan ravi]

look at the edited answer now

[Albert Barajas]

thank you !

[madhan ravi]

accept the answer so that other people know that you got the answer for your question

[sharmeen shahid]

why don't you use the sin(x) part?

[madhan ravi]

Missed it by mistake , check the edited answer now

Answer 3

[noor]

g(x)=cos⁡x-sin⁡x-0.5+x

[Voss]

If you want to plot the function g(x), you can adapt @Image Analyst's answer:

% Choose a range for x and use 500 points.
X = linspace(-20, 20, 500);
% Create Y
Y = cos(X) - sin(X) - 0.5 + X;
% Plot the function.
plot(X, Y, 'b-', 'LineWidth', 2);
grid on;
xlabel('X', 'FontSize', 15);
ylabel('Y', 'FontSize', 15);
title('cos(X) - sin(X) - 0.5 + X', 'FontSize', 15);
axis equal;
% Make a black line at the x and y axes
line(xlim, [0, 0], 'Color', 'k', 'LineWidth', 2);
line([0, 0], ylim, 'Color', 'k', 'LineWidth', 2);