Ho do i convert this number to an integer?

I'm using this code to solve an equation.

syms b

w=1150;di=32.59;do=23.44;

sol=solve((w-(2.*90.*sind(b))).^2==(w-(90.*sind(b+di))-(90.*sind(b-do))).^2+((90.*cosd(b-do))-(90.*cosd(b+di))).^2,b);

vpa(sol)

I'm solving for b and im supposed to get around 28.1606 but im getting

ans =

144.93095960237559740993061817135 + 177.92191183196224178797359740301i

Why am i not gettin gthe answer? Do i have to onvert it?

Answer 1

[Birdman]

Try vpasolve:

w=1150;di=32.59;do=23.44;
sol=vpasolve((w-(2.*90.*sind(b))).^2==(w-(90.*sind(b+di))-(90.*sind(b-do))).^2+((90.*cosd(b-do))-(90.*cosd(b+di))).^2,b)

vpasolve solves the equation numerically.

[Bharatha Ravi]

Thank you!

If suppose i needed to give various vaues of w, How could i give it? Like in a matrix form

[Birdman]

Simple for loop should help. Consider the following example:

w=[1150;1250;1350];di=32.59;do=23.44;
for i=1:numel(w)
    sol(i)=vpasolve((w(i)-(2.*90.*sind(b))).^2==(w(i)-(90.*sind(b+di))-(90.*sind(b-do))).^2+((90.*cosd(b-do))-(90.*cosd(b+di))).^2,b);
end

[Bharatha Ravi]

oh ok! Thank you so much!!

[Bharatha Ravi]

im getting this error:

Undefined function or variable 'b'.

Error in trial (line 9)

sol(i)=vpasolve((w(i)-(2.*90.*sind(b))).^2==(w(i)-(90.*sind(b+di))-(90.*sind(b-do))).^2+((90.*cosd(b-do))-(90.*cosd(b+di))).^2,b);

[Birdman]

I forgot to define b:

syms b
w=[1150;1250;1350];di=32.59;do=23.44;
for i=1:numel(w)
    sol(i)=vpasolve((w(i)-(2.*90.*sind(b))).^2==(w(i)-(90.*sind(b+di))-(90.*sind(b-do))).^2+((90.*cosd(b-do))-(90.*cosd(b+di))).^2,b);
end

[Bharatha Ravi]

The error isn't appearing anymore. But i am not getting any output.

[Birdman]

Type

sol

at the command line and you will see the results.

[Bharatha Ravi]

Thanks a ton birdman!!!

[Bharatha Ravi]

Is there any mistake in this:

syms b

l=1550;R=[2500;2600;2700;2800];w=1150;

for i=1:numel(R)

di(i)=atand(l./(R(i)-(w/2)));do(i)=atand(l./(R(i)+(w/2)));

sol=vpasolve((w-(2.*90.*sind(b))).^2==(w-(90.*sind(b+di(i)))-(90.*sind(b-do(i)))).^2+((90.*cosd(b-do(i)))-(90.*cosd(b+di(i)))).^2,b);

end

sol

i should be getting 4 answers but im getting only 1...which i dont is right or wrong.

what corrections should i make?

[Birdman]

Replace the line

sol=vpasolve((w-(2.*90.*sind(b))).^2==(w-(90.*sind(b+di(i)))-(90.*sind(b-do(i)))).^2+((90.*cosd(b-do(i)))-(90.*cosd(b+di(i)))).^2,b);

with

sol(i)=vpasolve((w-(2.*90.*sind(b))).^2==(w-(90.*sind(b+di(i)))-(90.*sind(b-do(i)))).^2+((90.*cosd(b-do(i)))-(90.*cosd(b+di(i)))).^2,b);

[Bharatha Ravi]

Awesome!! Thank you tons again!