(√6-√2)/4.设直角三角形ABC,《C=30度,〈B=90度,〈BAC=60度,延长BC至D,使AC=CD,设AB=1,AC=2,BC=√3,则〈ACB=2〈D,〈D=15度.BD=2+√3,AD=√(8+4√3)=√6+√2,
AB/AD=1/(√6+√2)=(√6-√2)/4
(√6-√2)/4.设直角三角形ABC,《C=30度,〈B=90度,〈BAC=60度,延长BC至D,使AC=CD,设AB=1,AC=2,BC=√3,则〈ACB=2〈D,〈D=15度.BD=2+√3,AD=√(8+4√3)=√6+√2,
AB/AD=1/(√6+√2)=(√6-√2)/4