f(x)=2sinx^2+sin2x属于求f(x)为正时值的集合

问题描述:

f(x)=2sinx^2+sin2x属于求f(x)为正时值的集合

f(x)=2sinx^2+sin2x=1-cos2x+sin2x=1+√2sin(2x-π/4)>0∵x∈(0,2π) ∴2x-π/4∈(-π/4,15π/4)sin(2x-π/4)>-√2/2画函数图象:得2x-π/4∈(-π/4,5π/4)∪(7π/4,13π/4)∴x∈(0,3π/4)∪(π,7π/4...