Actually it is not very difficult. Well okay, let me complete the thing then. .... <=> (c^2 + 64/17)^2 = 8448/17^2 <=> c^2 + 64/17 = sqrt( 8448/17^2 ) V c^2 + 64/17 = -sqrt( 8448/17^2 ) <=> c = sqrt( sqrt( 8448/17^2 ) -64/17 ) V c^2 = sqrt( -sqrt ( 8448/17^2 ) -64/17 ) => c = (rounded) 1.28 V c = sqrt( -9.17 ) Well, next time I find some time I will post all the squareroots of -9.17.