SOLUTION: exact value of sin 255

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Question 755553: exact value of sin 255
Answer by lwsshak3(11628) About Me  (Show Source):
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exact value of sin 255
sin (255)=sin(135+120)=sin135 cos120+cos135 sin120
sin135º=√2/2*-1/2-√2/2*√3/2 =-√2/4-√6/4=-(√2+√6)/4
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calculator check:
sin255º≈-0.9659..
exact value=-(√2+√6)/4≈-0.9659