设角a=-35π/6,2sin(兀+a)cos(兀-a)-cos(兀+a)/1+sin^2a+sin(兀-a)-cos^2(兀+a)值等于

设角a=-35π/6,2sin(兀+a)cos(兀-a)-cos(兀+a)/1+sin^2a+sin(兀-a)-cos^2(兀+a)值等于
设角a=-35π/6,2sin(兀+a)cos(兀-a)-cos(兀+a)/1+sin^2a+sin(兀-a)-cos^2(兀+a)值等于

设角a=-35π/6,2sin(兀+a)cos(兀-a)-cos(兀+a)/1+sin^2a+sin(兀-a)-cos^2(兀+a)值等于
[2sin(兀+a)cos(兀-a)-cos(兀+a)]/[1+sin^2a+sin(兀-a)-cos^2(兀+a)]利用诱导公式对原式化简=[2sinacosa+cosa]/[1+sin^2a+sina-cos^2a]利用1=sin^2a+cos^2a公式对上式化简= [2sinacosa+cosa]/[2sin^2a+sina]=cosa/sina=cota a=-35π/6 代入cot(-35π/6 )=cot(-6π+π/6)=cot(π/6)=根号3