Calculate sin 150=?

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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**

sin 150 =sin(90+60) = cos60 =1/2.

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