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Find the exact value of tan 5pi/12 using the half-angle identity.

  • Trig -

    tan 5pi/6 = -1/√3

    tan x/2 = (1-cos(x))/sin(x)

    cos 5pi/6 = -√3/2
    sin 5pi/6 = 1/2

    tan 5pi/12 = (1 + √3/2)/(1/2)
    = 2 + √3

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