C-03-Q041mediumsingle_mcqIf a+b+c=15a+b+c=15a+b+c=15 and a2+b2+c2=83a^2+b^2+c^2=83a2+b2+c2=83, ab+bc+ca=?ab+bc+ca = ?ab+bc+ca=?a717171b142142142c353535d5050