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Calculate sin 150=?

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colorcolour | Student, College Freshman | (Level 1) Honors

Posted May 9, 2010 at 12:57 AM via web

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Calculate sin 150=?

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giorgiana1976 | College Teacher | (Level 3) Valedictorian

Posted May 9, 2010 at 1:02 AM (Answer #1)

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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

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neela | High School Teacher | (Level 3) Valedictorian

Posted May 9, 2010 at 1:06 AM (Answer #2)

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

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