不求值比较大小(单调性求)cos[(-47/10)派]与cos[(-44/9)派]
热心网友
cos(-47/10*pi)=cos(-2pi-7/10*pi)=cos(-7pi/10)=cos(7pi/10)cos(-44/9*pi)=cos(-2pi-8pi/9)=cos(-8pi/9)=cos(8pi/9)在区间(0,pi)内y=cosx是减函数.又0cos(8pi/9)---cos(-47pi/10cos(-44pi/9)
不求值比较大小(单调性求)cos[(-47/10)派]与cos[(-44/9)派]
cos(-47/10*pi)=cos(-2pi-7/10*pi)=cos(-7pi/10)=cos(7pi/10)cos(-44/9*pi)=cos(-2pi-8pi/9)=cos(-8pi/9)=cos(8pi/9)在区间(0,pi)内y=cosx是减函数.又0cos(8pi/9)---cos(-47pi/10cos(-44pi/9)