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I rested on this tutorial.

After issuing the command with "solve" function:

%i2 solve((a-b-sqrt(-c^2+2*c*y-y^2+r^2))^2+(d-y)^2=2*r^2*(1-cos(e)),y);

The output is: enter image description here

Why there is unknown quantity "y" on the right side?

P.S.

There's no "Maxima" tag, what a pity! However, I was redirected here by a stackoverflow moderator, so I assume it is not offtopic.

Maxima is a computer algebra system based on a 1982 version of Macsyma. It is written in Common Lisp and runs on all POSIX platforms such as Mac OS X, Unix, BSD, and GNU/Linux as well as under Microsoft Windows. It is free software released under the terms of the GNU General Public License.
source: http://en.wikipedia.org/wiki/Maxima_%28software%29

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Clearly, Maxima was not entirely successful at isolating the variable you want... –  J. M. Jul 23 '12 at 0:42
    
@J.M. Was it my fault? –  0x6B6F77616C74 Jul 23 '12 at 0:47
    
W|A spits out a pretty lengthy result that doesn't seem to have $y=$ (something with $y$ in it)... –  The Chaz 2.0 Jul 23 '12 at 0:50
    
@TheChaz there are two "y" under the square root. Or this "W|A" shortcut which I don't understand (google also doesn't know anything about "W|A maxima") is significant. –  0x6B6F77616C74 Jul 23 '12 at 1:05
1  
I copied your code "solve(...,y)" into www.wolframalpha.com –  The Chaz 2.0 Jul 23 '12 at 1:16

1 Answer 1

up vote 3 down vote accepted

The general solve command in Macsyma has limited capabilities for dealing with algebraic functions. You can work around this by using the rational function package as in the code below. There I define w to be the sqrt, then solve for w, square, then solve for y.

(algebraic:true, tellrat( w^2 = -c^2+2*c*y-y^2+r^2 ));

solve(rat(solve(rat((a-b-w)^2+(d-y)^2 = 2*r^2*(1-cos(e))),w)^2),y)

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This is useful. –  copper.hat Jul 23 '12 at 3:01
    
The result is five lines long, like in the wolframalpha.com. –  0x6B6F77616C74 Jul 23 '12 at 14:53

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