Why is sin(40) not equal to cos(50) on google calculator?

If we draw the right-angled triangle ABC, where ABC=90 degrees, AC is the hypotenuse, BAC=40 degrees and ACB=50 degrees, AC=1, then sin(40) should be equal to BC/AC or BC/1 or BC. Also, cos(50) should be equal to BC/AC or BC/1 or BC. If this is so (i could be wrong, please explain why if you think so) then cos(50) = sin(40), however on google calculator cos(50) = 0.964966028 yet sin(40) = 0.74511316. Please explain where i went wrong! Thanks.