已知
f(x)=2cos(−x)cosx−cos2x,x∈R,
(1)求
f()的值;
(2)当x∈
[0,]时,求f(x)的最值.
人气:429 ℃ 时间:2020-09-24 18:09:30
解答
(1)∵f(x)=2sinxcosx-3cos2x=sin2x-3cos2x=2sin(2x-π3),∴f(π6)=2sin(2•π6-π3)=0;(2)∵x∈[0,π2]时,∴2x-π3∈[-π3,2π3],∴sin(2x-π3)∈[-32,1],∴2sin(2x-π3)∈[-3,2],∴f(x)max...
推荐
猜你喜欢