解；（1）f(x)＝cos2x+3sinxcosx+1=12cos2x+32sin2x+32=sin（2x+π6）+32函数的周期T=2π2=π∵-1≤sin（2x+π6）≤1∴12≤sin（2x+π6）+32≤52即12≤f（x）≤52（2）当-π2+2kπ≤2x+π6≤π2+2kπ⇒x∈[-π3+kπ...