已知函数f(x)=2sinx(sinx+cosx)(1)求f(x)的最小正周期和最大值
问题描述:
已知函数f(x)=2sinx(sinx+cosx)(1)求f(x)的最小正周期和最大值
f(x)=2(sinx)^2+sin2x=1-cos2x+sin2x=1+√2sin(2x-π/4)中1-cos2x+sin2x=1+√2sin(2x-π/4)怎么得到的????最大值怎么求?详细过程!!
答
f(x)=2sinx(sinx+cosx)
=2sin²x+2sinxcosx
=1-cos2x+sin2x
=1+√2 (√2/2sin2x-√2/2cos2x)
=1+√2(sin2xcosπ/4-cos2xsinπ/4)
=1+√2sin(2x-π/4)
所以
最小正周期=π
最大值=1+√2