若f(x)=sin(2x+π/12)
问题描述:
若f(x)=sin(2x+π/12)
(1)求f(x)
的对称轴方程、对称点坐标
(2)求f(x)的单调增区间
(3)若f(x)=1/3,求sin(11/12π-2x)+sin^2(5/12π-2x)的值
改:(3)若f(x)=1/3,求sin(11π/12-2x)+sin^2(5π/12-2x)的值
答
1.对称轴2x+π/12=π/2+kπ,x=5π/24+kπ/2,k属于z,
对称点2x+π/12=kπ,x=-π/24+kπ/2k属于z,
2.
单调增区间
2kπ-π/2≤2x+π/12≤2kπ+π/2
解得:kπ-π/6≤x≤kπ+5π/6改:(3)若f(x)=1/3,求sin(11π/12-2x)+sin^2(5π/12-2x)的值sin(11π/12-2x)+sin^2(5π/12-2x)=sin【π/2+(5π/12-2x)】+sin^2(5π/12-2x)=cos(5π/12-2x)-sin^2(5π/12-2x)=cos【π/2-(π/12+2x)】-sin^2【π/2-(π/12+2x)】=sin(π/12+2x)-cos^2(π/12+2x)=sin(π/12+2x)-(1-sin^2)(π/12+2x)=sin(π/12+2x)-(π/12+2x)+sin^2(π/12+2x)∵f(x)=1/3∴原式=1/3+1/9-(π/12+2x)这里的(π/12+2x)不知道怎么做、、你在思考下吧、、