请问怎么证明cosnx*sinx+sinnx*cosx=sin(n+1)*x?
请问怎么证明cosnx*sinx+sinnx*cosx=sin(n+1)*x?
三角恒等变换证明cosx+cos2x+…+cosnx=[cos(n+1/2)·sinnx/2]/sinx/2怎么证明?
设n∈N*,且sinx+cosx=-1,则sinnx+cosnx=______.
证明:cosnx+i sinnx 等于(cosx+i sinx)的n次方.
用数学归纳法证明:sinx+sin2x+sin3x+……+sinnx=[sin(nx/2)sin((n+1)x/2)]/
求证:cosx+cos2x+...+cosnx={[cos(n+1)x/2]*[sin(n/2)x]}/[sin(x/2
1-cosX/sinX=tan(X/2) 请问怎么证明,
已知函数f(x)=cosnx/(sinnx-1),且f'(x)不在x=π/4上连续,则n的最小正整数值为
COSX+COS2X+COS3X+COS4X+COS5X+COS6X+...+COSNX=1/2|{SIN(N+1/2)
SinX+1-cosX/sinX-1+cosX=1+tan(X/2)/1-tan(X/2) 请问怎么证明,
请问怎么证明sinX+sin(X+Y)+sin(X+2Y)/cosX+cos(X+Y)+cos(X+2Y)=tan(X+
证明成立:[cos(3x)-sin(3x)]/(cosx+sinx)=1-2sin(2x).