1.求下列各函數(shù)的最大值,最小值和周期; (1)y=2cosx; (2)y=-5cos(-x).
1.求下列各函數(shù)的最大值,最小值和周期;
(1)y=2cosx;
(2)y=-5cos(-x).
2.比較下列各對余弦值的大小:
(1)cos515°和cos530°
(2)cos(15π/8)和cos(14π/9)
(3)cos(-25π/6)和cos(-31π/7)
1.求下列各函數(shù)的最大值,最小值和周期;(1)y=2cosx;
ymax=2*1=2
ymin=2*(-1)=-2
T=2π
(2)y=-5cos(-x).
ymax=-5*(-1)=5
ymin=-5*1=-5
T=2π
2.比較下列各對余弦值的大小:(1)cos515°和cos530°
cos515°=cos205°=-cos25°
cos530°=cos190°=-cos10°
∵cos25°
∴cos515°>cos530°???????????(2)cos??15??/8????cos??14??/9??cos??15??/8??=cos????/8??cos??14??/9??=cos??4??/9????cos????/8??>cos??4??/9????cos??15??/8??>cos??14??/9??(3)cos(-25??/6)??cos(-31??/7)cos(-25??/6)=cos(-??/6)=cos(??/6)cos(-31??/7)=cos(-3??/7)cos(3??/7)??cos????/6??>cos??3??/7????cos(-25??/6)>cos(-31??/7)л??(๑•ั็??•็ั๑)????л