1.cosπ/3-tan9π/4+3/4tan²（-2π+π/6)+sin25π/6-cos²13π/6+sin17π/2 2.a,b,c为正数3的a次方=4的b次方=6的c次方证：2/a+1/b=2/c 3.sinx+cos+x=1/5(0＜x＜π）求tanx

解答(1)cos(-11π/6) (2)tan9π/4 (3)sin1140° 计算sin25/6π+tan9/4π-cos19/3π 计算sin25/6π+tan9/4π-cos19/3π tan9分之π+tan9分之2π+根号3乘tan9分之π乘tan9分之2π的值 求下列各三角函数值：(1)cos(-11π/6) (2)tan9π/4 (3)sin1140° 化简 {sin(π+α)cos(α-2π)tan9π/4}/sin(-α)sin(7π/2+α)过程 tan9*tan27+tan27*tan54+tan54*tan9都是说度数,本来是π/20,3π/20+.急啊! tan9π/8 tan9..3等于多少 1.cosπ/3-tan9π/4+3/4tan²（-2π+π/6)+sin25π/6-cos²13π/6+sin17π/2 2.a,b,c为正数3的a次方=4的b次方=6的c次方证：2/a+1/b=2/c 3.sinx+cos+x=1/5(0＜x＜π）求tanx tan9/4的结果不会怎么算额= =！ 计算：cos（π/5)+cos（2π/5)+cos(3π/5)+cos(4π/5) 求值:cos(π/11)cos(2π/11)cos(3π/11)cos(4π/11)cos(5π/11) 求值：cos(π/11)-cos(2π/11)+cos(3π/11)-cos(4π/11)+cos(5π/11) cos(π/11)cos(2π/11)cos(3π/11)cos(4π/11)cos(5π/11) 比较大小 1/(tan(-13π/7)),1/(tan9π/8) 试比较tan(-13π/7).tan9π/8,tan3的大小 化简cosθ+cos(θ+2π/3)+cos(θ+4π/3)