Satisfying an equation using random numbers

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Daniel Porter
Daniel Porter on 26 Mar 2019
Commented: Adam Danz on 26 Mar 2019
I have chosen ten random values for theta using theta = pi*(1/2 - 1*rand(1,10)).
Now I want to prove that for these 10 randomly chosen numbers,
sqrt((1-sin(theta)) / (1+sin(theta))) = (1-tan(theta/2)) / (1+tan(theta/2))
I set the left hand side equal to the variable lhs and the right hand side equal to the variable rhs, however they are giving me different values!
How would you go about proving lhs = rhs with these 10 random values?
  2 Comments
Daniel Porter
Daniel Porter on 26 Mar 2019
The question that i am doing says that these two sides are equal.
Also when I put any value between -pi/2 and pi/2 into both these sides, they give out the sasme answer. This is in my calculator however, not in MatLab.
I want to see how this can be accomplished in Matlab.
Cheers
Adam Danz
Adam Danz on 26 Mar 2019
I see. You're just missing the period before the division.
./
see KALYAN ACHARJYA's answer below.

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Answers (1)

KALYAN ACHARJYA
KALYAN ACHARJYA on 26 Mar 2019
Edited: KALYAN ACHARJYA on 26 Mar 2019
theta=pi*(1/2-1*rand(1,10));
LHS=sqrt((1-sin(theta))./(1+sin(theta)));
RHS=(1-tan(theta/2))./(1+tan(theta/2));
If your check the values
>> LHS
LHS =
4.1859 1.2110 9.0071 1.9375 1.3009 3.3514 5.1984 57.4074 0.0008 4.6604
>> RHS
RHS =
4.1859 1.2110 9.0071 1.9375 1.3009 3.3514 5.1984 57.4074 0.0008 4.6604
>> LHS-RHS
ans =
1.0e-12 *
0.0009 0.0002 0.0036 0.0002 0 -0.0004 -0.0018 0.9237 -0.0064 -0.0018
Please note the difference is not equal zero.
>> isequal(LHS,RHS)
ans =
0
Logic Zero That menas not equal in Matlab, Please read about limit of floating point representation or look here
Other case
>> A=[1 2 3];
>> B=[1 2 3];
>> isequal(A,B)
ans =
1
Hope it helps!

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