由空渗cos(a)+cos^2(a)=1得cos(a)=sin^2(a),又因为sin^2(a)+cos^2(a)=1所昌亏册以sin^4(a)+sin^2(a)=1,sin^2(a)=(根号5-1)/2,sin^4(a)=(耐宏3-根号5)/2sin^2(a)+sin^6(a)=1+sin^6(a)-sin^4(a)=1+sin^4(a)(sin^2(a)-1)=1+(3-根号5)/2(根号5-3)/2=(3根号5-5)/2