10．已知函数f(x)=sinx+tanx−2xf(x)=\sin x+\tan x-2xf(x)=sinx+tanx−2x．（1）证明：函数f(x)f(x)f(x)在(−π2,π2)(-\frac{\pi }{2},\frac{\pi }{2})(−2π,2π)上单调递增；（2）若x∈(0,π2)x\in (0,\frac{\pi }{2})x∈(0,2π)，f(x)>mx2f(x)>mx^{2}f(x)>mx2，求mmm的取值范围．