Question

Which is greater, Sin 40° or Cos 40°?

Answer 1

sin 40 = 0.6428
cos 40 = 0.7660
thus cos 40 is greater than sin 40

Answer 2

this question is based on calculus (e.g increasing or decreasing functions )

in simple way ,
value of sine 0 to 90 degree
you see sine in this interval increase
0 to 1
but cosine value 0 to 90 degree decrease 1 to 0

it means higher the angle means lower the value of cosine . but for sine higher the value of angle higher value of sine only 0 to 90degree interval .

we do first ,
convert cosine to sine
we know cos (90-x) = sinx
hence, cos40 =sin50 -----(1)

now , we have sin40 and sin50
you now easily ask which value is large .
sin50 value large then sin40
hence, cos40 value large then sin40