I didn't understand it how they completed it?

[John D'Errico]

Please stop posting your homework questions with no effort made. Future questions like this will be closed as soon as I see them, if you cannot make an effort. Homework is yours to do.

[Sam Chak]

Hi @Mohit

It appears that you have two open questions that have been answered, but you have not followed up to provide an update. Instead, you have opened a third homework question. I would encourage you to take some time to review the solutions provided for the other two homework questions:

https://www.mathworks.com/matlabcentral/answers/2142681-how-to-approach-this-type-of-question-in-matlab

https://www.mathworks.com/matlabcentral/answers/2142856-im-unable-to-start-this-question-and-dont-know-how-to-approach-it

By reviewing the provided solutions, you may gain a better understanding of how to approach and complete these types of problems in MATLAB. Taking the time to thoroughly understand the previous solutions can help you make progress on your current homework question.

Answer 1

[VBBV]

@Mohit Define the symbolic variables d & theta for the given equation to be solved

%  
syms d theta 
x = [d theta]; % define a symbolic vector of unknown variables , depth (d) and theta 
fminsearch(@f,[25 1.5])  % give initial values based on the answer options and solve using fminsearch

ans = 1x2

14.8119 1.0472

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% use explicit function call 
function y = f(x)
  y = 380./x(1) - x(1)/tan(x(2)) + 2*x(1)/sin(x(2));
end

[Walter Roberson]

? Defining the symbolic variables does not appear to do anything useful here??

Maybe if you had used

syms d theta 
x = [d theta]; % define a symbolic vector of unknown variables , depth (d) and theta 
f(x)

ans = 

fminsearch(@f,[25 1.5])  % give initial values based on the answer options and solve using fminsearch

ans = 1x2

14.8119 1.0472

<mw-icon class=""></mw-icon>

<mw-icon class=""></mw-icon>

% use explicit function call 
function y = f(x)
  y = 380./x(1) - x(1)/tan(x(2)) + 2*x(1)/sin(x(2));
end