Question

比较大小: sin515°与sin530° cos 15π/8 与cos14π/9 tan(-13π/4) 与tan(-17π/5)

Answer 1

sin515=sin(360+155)=sin155=sin(180-25)=sin25
sin530=sin(360+170)=sin170=sin(180-10)=sin10
sin25>sin10 所以sin515>sin530
cos15π/8=cos(2π-π/8)=cosπ/8
cos(14π/9)=cos(2π-4π/9)=cos4π/9
cosπ/8>cos4π/9 所以cos15π/8>cos14π/9
tan(-13π/4)=tan(-3π-π/4)=-tanπ/4
tan(-17π/5)=tan(-3π-2π/5)=-tan2π/5
tan2π/5>tanπ/4 所以-tanπ/4>-tan2π/5 所以tan(-13π/4)>tan(-17π/5)