已知函数f(x)=2sin(1/5x+5派/6) 求f(0)的值

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已知函数f(x)=2sin(1/5x+5派/6) 求f(0)的值
已知函数f(x)=2sin(1/5x+5派/6) 求f(0)的值

已知函数f(x)=2sin(1/5x+5派/6) 求f(0)的值
f(x)=2sin(1/5x+5派/6)
=2sin(1/5x+派-派/6)
=2sin{派-(派/6-1/5x)}
=2sin(派/6-1/5x)
=-2sin(1/5x-派/6)
f(0)=-2sin(0-派/6)=1
用以上这种方法或下面的方法
f(0)=2sin(0+5派/6)=2sin(5派/6)=2sin(派-派/6)=2sin(派/6)=1

答案:f(0)=-1

当x=0时
f(0)=2sin(0+5π/6)=2sin30°=1

2sin(5/6π+0)=2sin(1-1/6π)=2sin1/6π=2* 1/2 =1

1/5x应该是x/5吧。f(0)=2sin(0+5π/6)=2sin5π/6=2sin(π-π/6)=2sinπ/6=1