求证sin1°/【cosn°*cos(n+1)°】=tan(n+1)°-tann°
求证cos(720°+α)(2/cosα+tanα)(1/cosα-2tanα)=2cosα-3tanα
三角函数问题cosacos2a - 1 = cos3a cos2acos(n-1) - cos(n-2)a = cosn
A sin1>sin1° B sin1
求证sin3°=(sin^2°-sin^1°)/sin1°
lim1/n(sin1/n+……+sin(n-1)/n)=?n趋向无穷大
求极限lim(x→无穷)1/n{(1+cosπ/n)^(1/2)+.+(1+cosn*π/n)^(1/2)} ..
利用欧拉公式证明cosθ+cos2θ+cos3θ+···+cosnθ=-1/2+sin(n+1/2)θ/sin(θ/2)
sin1 sin2 sin3 什么意思?是sin1°?还是sin1?
求证:(1/sinα-sin(180°+α))/(1/cos(540°-α)+cos(360°-α))=1/(tanα)
求极限:lim(x→0)[cosx+cos^x+cos3(次方)x+……+cosn(次方)x] /(cosx-1),[n
.若f(x)={sin(n派-x)cos(n派+x)/cos[(n+1)派-x]}*tan(x-n派)cot[(n派/2
设n>=2,当x不等于k派,求证:tanx*tan2x+tan2x*tan3x+.+tan(n-1)*tannx=tan