不等式sinx-cosx>1的解集是?
∵sinx-cosx
=√2[sinx×(√2/2)-cosx×(√2/2)]
=√2[sinx×cos(π/4)-cosx×sin(π/4)]
=√2sin[x-(π/4)]>1
∴sin[x-(π/4)]>√2/2
∴观察函数y=sinx的图像可知：
2kπ+(π/4)
不等式sinx-cosx>1的解集是?
∵sinx-cosx
=√2[sinx×(√2/2)-cosx×(√2/2)]
=√2[sinx×cos(π/4)-cosx×sin(π/4)]
=√2sin[x-(π/4)]>1
∴sin[x-(π/4)]>√2/2
∴观察函数y=sinx的图像可知：
2kπ+(π/4)