Trig Identities
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What two angles could you use to find the exact value of sin 105 degrees without a calculator?
60+45
Simplify using the compound angle formula in reverse: cos2xcosx+sin2xsinx
cos(2x-x)
Without your calculator, show: cos75degrees = root6 - root2/ 4
cos(45+30) Use sum and difference formulas
Expand and simplify: sin(90degrees + theta)
costheta
Prove sin2u = 2sinucosu
sin (u+u) = sinucosu +sinucosu = 2sinucosu
Sum and Difference Formulas
sin(u+/- v)= sinucosv +/- cosusinv cos (u+/- v)= cosucosv -/+ sinusinv
Double Angle IDs
sin2u= 2sinucosu cos2u = cos^2u-sin^2u cos2u = 2cos^2u-1 cos2u = 1-2sin^2u
Pythagorean Identities
sin^2u+cos^2u=1 1+tan^2u=sec^2u 1+cot^2u=csc^2u
