Explain why sin (1/k) is positive for k >= 3 ?

Answer 1

sines are positive in quadrant I& II where angles are between zero and 180 degrees

0 < 1/x < 180 when x>1/180. 3>1, if x>1/180, x is also >3, so

0 < 1/x < 180 when x>3

or, if you're measuring angles in radians

then

0<1/x<pi and

0<1/x< pi when x> 1/pi and when x>3