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if sin a=0.5 then find the value of cos3a

  • mathematics -

    sin(a)=0.5
    use sin²(a)+cos²(a)=1
    0.5²+cos²(a) = 1
    cos²(a)=3/4
    cos(a)=sqrt(3)/2
    cos³(a)=(3/8)sqrt(3)

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