三角函数题.已知tanx=2.求(sin(π-x)cos(2π-x)sin(-x+3π/2))/tan(-x-π)sin(-π-x)的值已知tanx=2.求(sin(π-x)cos(2π-x)sin(-x+3π/2))/tan(-x-π)sin(-π-x)的值.过程具体点,最好给出公式.
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![三角函数题.已知tanx=2.求(sin(π-x)cos(2π-x)sin(-x+3π/2))/tan(-x-π)sin(-π-x)的值已知tanx=2.求(sin(π-x)cos(2π-x)sin(-x+3π/2))/tan(-x-π)sin(-π-x)的值.过程具体点,最好给出公式.](/uploads/image/z/1985111-71-1.jpg?t=%E4%B8%89%E8%A7%92%E5%87%BD%E6%95%B0%E9%A2%98.%E5%B7%B2%E7%9F%A5tanx%3D2.%E6%B1%82%28sin%28%CF%80-x%29cos%282%CF%80-x%29sin%28-x%2B3%CF%80%2F2%29%29%2Ftan%28-x-%CF%80%29sin%28-%CF%80-x%29%E7%9A%84%E5%80%BC%E5%B7%B2%E7%9F%A5tanx%3D2.%E6%B1%82%28sin%28%CF%80-x%29cos%282%CF%80-x%29sin%28-x%2B3%CF%80%2F2%29%29%2Ftan%28-x-%CF%80%29sin%28-%CF%80-x%29%E7%9A%84%E5%80%BC.%E8%BF%87%E7%A8%8B%E5%85%B7%E4%BD%93%E7%82%B9%2C%E6%9C%80%E5%A5%BD%E7%BB%99%E5%87%BA%E5%85%AC%E5%BC%8F.)
三角函数题.已知tanx=2.求(sin(π-x)cos(2π-x)sin(-x+3π/2))/tan(-x-π)sin(-π-x)的值已知tanx=2.求(sin(π-x)cos(2π-x)sin(-x+3π/2))/tan(-x-π)sin(-π-x)的值.过程具体点,最好给出公式.
三角函数题.已知tanx=2.求(sin(π-x)cos(2π-x)sin(-x+3π/2))/tan(-x-π)sin(-π-x)的值
已知tanx=2.求(sin(π-x)cos(2π-x)sin(-x+3π/2))/tan(-x-π)sin(-π-x)的值.过程具体点,最好给出公式.
三角函数题.已知tanx=2.求(sin(π-x)cos(2π-x)sin(-x+3π/2))/tan(-x-π)sin(-π-x)的值已知tanx=2.求(sin(π-x)cos(2π-x)sin(-x+3π/2))/tan(-x-π)sin(-π-x)的值.过程具体点,最好给出公式.
因为sin(π-x)=sinx,cos(2π-x)=cosx,sin(-x+3π/2)=sin(3π/2-x)=-cosx,tan(-x-π)=-tan(π+x)=-tanx,sin(-π-x)=-sin(π+x)=sinx
所以
原式=[sinx×cosx×(-cosx)]/(-tanx×sinx)
=cos²x/tanx
因为tanx=sinx/cosx=2
所以sinx=2cosx
因为 sin²x+cos²x=1
所以 (2cosx)²+cos²x=1
4cos²x+cos²x=1
5cos²x=1
cos²x=1/5
所以
原式=(1/5)/2=1/10