Demonstrate that sin 6

We know that the number pi=3.14 (approx.), so, if we'll calculate:

 2pi=6.28 and 2*pi-pi/2=(3*pi)/2=1.5*pi=4.71

From the results above, 6 belongs to the interval (3pi/2,2pi), meaning 6 is in the IV-th quadrant.

In the IV-th quadrant, sine function is negative, so sin 6<0.