Calculate sin 150=?

To find out the value of sin 150 , we'll choose to use the
formula:

sin(a-b) = sin a cos b - sin b cos
a

We'll write 150 as 180-30, so sin 150 = sin
(180-30)

sin (180-30) = sin 180 cos 30 - sin 30 cos
180

sin180 = 0

sin 30 =
1/2

cos 30 = sqrt3/2

cos 180 =
-1

sin 180 cos 30 - sin 30 cos 180 =
0-(1/2)(-1)=1/2

sin150 = sin30 =
1/2