Question

which is bigger sin 55* or cos55*

Answer 1

sin 55
------------  =  tan 55
cos 55

we know tan Ф  is positive and increasing in  (0 , π/2 )  from  0 to infinity.
tan 45 = 1  so tan 55  > tan 45 = 1 
so tan 55 > 1
so sin 55 > cos 55

Answer 2

sin55 bigger than cos55