Question #b2b3e

2 Answers
Aug 23, 2017

-11

Explanation:

We can add multiples of 2pi2π to (-5pi)/25π2 to find coterminal angles.

(-5pi)/2+2pi=-pi/25π2+2π=π2

This is located on the yy-axis between Quadrant "III"III and Quadrant "IV"IV.

The point on the unit circle at this location is (0,-1)(0,1), so

sin((-5pi)/2)=sin(-pi/2)=-1sin(5π2)=sin(π2)=1

Aug 23, 2017

-1

Explanation:

sin(-5 pi)/25π2= - sin (5pi)/25π2

= -sin (2pi + pi/2)(2π+π2)

= - sin pi/2π2 = -1