Cosine in radians (DRG: DEG → RAD)
The cosine of in radians. Press 
once to switch from degrees to radians. Then press 
, 
, 
, 
, type 4, and 
. The brackets make the whole fraction the angle. Press 
: 0.707106781.
The cosine of 4π in radians. Press once to switch from degrees to radians. Then press , , , , type 4, and . The brackets make the whole fraction the angle. Press : 0.707106781.
▶ Watch this step in the video (15:52)