Triple Spread Formula

$$ (s_1 + s_2 + s_3)^2 = 2(s_1^2 + s_2^2 + s_3^2) + 4s_1 s_2 s_3 $$

Solving for any one (WLOG, #1) yields

$$ s_1 = s_2 - s_3 -2s_2s_3 \pm \sqrt{4s_2s_3-s_2-s_3-s_2^2-s_3^2} $$

Geometry students will recognize this as an ASA or AAS situation. We can solve AA (angle-angle) situations for the third spread, but then we cannot find any quadrances.