[tan(5/4)π+tan(5/12)π]/[1-tan(5/12)π] =[tan(1/4)π+tan(5/12)π]/[1-tan(1/4)πtan(5/12)π]
=tan[(1/4)π+(5/12)π]=tan(2/3π)=-tan(1/3π)=-根号3