I was a MapleV user in the past (~25 years ago) an I'm very pleased to find such an elegant solution the sage is. I try to see how it works trying to solve an easy trigonometry calculation:
var('r,l,m')
ex = l/sin(m/2/r)-r
solve(ex,r)
[r == l/sin(1/2*m/r)]
Do not want, ok. To simplify I put some real values m and l and tried again:
exval = ex.subs(l=7.2,m=10)
solve(exval,r)
[r == 36/5/sin(5/r)]
still not solving, r=3.68357 is what I'm searching for. What would be a right way to proceed? Thank you in advance, v42
