tan(a+6π/5)=m则tan(a+π/5)=m[sin(π/5+a)+3cos(a+π/5)]/[sin(-π/5-a)-cos(a+π/5)]=[sin(π/5+a)+3cos(a+π/5)]/[-sin(π/5+a)-cos(a+π/5)]上下除以cos(a+π/5)且sin(a+π/5)/cos(a+π/5)=tan(a+6π/5)所以原...