If cos(t) = -sqrt.(21)/5, sin(t) = -2/5 tan(t) = 2sqrt.(21)/21

then what are the values of:

cos (2t)

sin (t/2)

tan (2t)

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- April 20th 2009, 05:22 PMNeedHelp18Help with double angle and half angle formulas
If cos(t) = -sqrt.(21)/5, sin(t) = -2/5 tan(t) = 2sqrt.(21)/21

then what are the values of:

cos (2t)

sin (t/2)

tan (2t) - April 20th 2009, 06:30 PMskeeter