(1) sin(-π/16)=-sin(π/16)
sin(-π/5)=-sin(π/5)
sin(π/16)-sin(π/5)
sin(-π/16)>sin(-π/5)
(2)cos(-33/5π)=cos(-7π+2/5π)=-cos(2/5π)
cos(-13/3π)=cos(-4π-1/3π)=cos(1/3π)
-cos(2/5π)