How do you evaluate sin (-8 pi / 12)?

2 Answers
Jun 8, 2016

-sqrt(3)/2

Explanation:

sin ( - (8 * pi )/12)

= sin ( - 120°)

= - sin ( 120° )

= - sin ( 180° - 60° )

= - sin ( 60° )

= -sqrt(3)/2

Jun 13, 2016

-sqrt(3)/2

Explanation:

-8*pi/12 =( pi/3) -pi

So,

sin(-8*pi/12) = sin((pi/3)-pi)

sin(-8*pi/12) = sin(-( pi - pi/3))

Knowing that :
sin(-alpha) = - sin(alpha)

sin(-8*pi/12) = - sin( pi - pi/3)

Knowing that:
sin(pi-alpha) =sin(alpha)

sin(-8*pi/12) = -sin(pi/3)

So,
sin(-8*pi/12) = -sqrt(3)/2