已知a=tan(-6分之7π),b=cos4分之23π,c=sin(-4分之33π),则a、b、c的大小关系是?

Question

已知a=tan(-6分之7π),b=cos4分之23π,c=sin(-4分之33π),则a、b、c的大小关系是?

Answer 1

tan(2π-7π/6)=tan(5π/6)=-√3/3
cos23π/4=cos(6π-π/4)=cos(-π/4)=cos(π/4)=√2/2
sin(-33π/4)=sin(-π/4)=-√2/2
而根3=1.7,根2=1.4
所以cos23π/4>tan(2π-7π/6)>sin(-33π/4)