用π/2=2/1*2/3*4/3*4/5*6/5*6/7*…前100项之积计算π.这样子写有什么错误.

用π/2=2/1*2/3*4/3*4/5*6/5*6/7*…前100项之积计算π.这样子写有什么错误. 已知sin(α+π/4)=3/5,π/2 已知cos(θ+π/4)=3/5,π/2 已知cos(a+π/4)=3/5,π/2 sin0=0 sin(1/6π)=1/2sin(1/3π)=√3/2sin(1/2π)=1sin(2/3π)=√3/2sin(5/6π)=1/2sin(π)=0sin(-π)=0sin(-5/6π)=-1/2sin(-2/3π)=-√3/2sin(-1/2π)=-1sin(-1/3π)=-√3/2sin(-1/6π)=-1/2sin(7/6π)=-1/2sin(4/3π)=-√3/2sin(5/3π)=-√3/2sin(11/6π)=-1/ tan(a-4π)cos(π+a)sin^2(a+3π)/tan(3t+a)cos^2(2/5π+2)=-2/1求cosa*|tana| sina+cosa=1/5且2a∈（π,3π/2)求cos2a,tan(2a-π/4) 已知sina=-4/5,a属于(π,3π/2),cosb=1/2,b属于(3π/2,2π)问：cos(a-b)的值 用π/2=1+1!/3+2!/(3*5)+3!/(3*5*7)+4!/(3*5*7*9)+.+n!/(3*5*...*(2n+1))公式求出π的近似值 函数y=tan(1/2x-π/3)的一个单调递增区间A、(-π/3,5π/3)B、(π/6,7π/6)C、(-2π/3,4π/3)D、(-π/6,5π/6) vb 求π近似值用公式：π=2*（2^2/1*3）*(4^2/3*5).(2n)^2/[(2n-1)*(2n+1)]用for 和 while 分别写一下, 已知a∈(5π/4,3π/2),cos(π/4+a)=3/5,求(sin2a+2(sina)^2)/(1-tana)的值 已知cosa=-4/5,a属于（π,3π/2)则sin(π/2)=? cos7π/3-sin^2(17π/4)-1/3tan^2(π/3)sin3π/2+cos0=? 23/4π=7π+2/3π怎么知道7π+2/3π,还有21/8π=2π+5/8π, cos(π+α)=-1/3,sin(3π/2-α)=sin(π/3+α)=1/3,cos(5π/6+α)=sin(α-π/4)=1/3,cos(π/4+α)= cosx=-4/5 x属于(π,3π/2)求1+tanx/2除以1-tanx/2 已知tan (π+ α)=-2/1,求下列各式的值(1)[2cos(π-α)-3sin(π+α)]/[4cos(α-2π)+sin(4π-α)](2)sin(α-2π)xcos(α+5π)