SOLUTION: Evaluate the expression using trig identities. State the identity that you use.
sin(pi/12)sin(5pi/12)
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-> SOLUTION: Evaluate the expression using trig identities. State the identity that you use.
sin(pi/12)sin(5pi/12)
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You can put this solution on YOUR website! Evaluate the expression using trig identities. State the identity that you use.
sin(pi/12)sin(5pi/12) ]
= sin(15 degrees)(sin(75 degrees)
= sin(45-30)*sin(45+30)
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= [sin45cos30+cos45*sin30]
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= [sin45cos30]^2 - [cos45sin30]^2
= [(sqrt(2)/2)(sqrt(3)/2)]^2 - [(sqrt(2)/2)(1/2)]^2
= [(sqrt(6)/4]^2 - [(sqrt(2)/4]^2
= 6/16 - 2/16
= 1/4
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Cheers,
Stan H.
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