A:1/2*S*r;
solve([A=S],[r]);
(%o6) (r*S)/2
(%o7) [r=2]
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how to solve if some variable is constant
> we have
> Q is a angle of sector
> r is a radius of sector
> S is a arc length of sector
> A is a area of sector
>
> question : if the value of A = the value of S, solve r=?
> that is clearly, r=2.
> A=S
> 1/2Sr=S
> so, r=2
>
> I try to do in maxima
> A:1/2*S*r;
> solve([A=S,r]);
> solve([1/2*S*r=S,r]);
>
> (%o13) (r*S)/2
> (%o14) [[S=0,r=0]]
> (%o15) [[S=0,r=0]]
> that can not answer r=2.
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