Maths

Evaluate in simple surd form the following:
(1) Sin 225
(2) Cos 195
(3) Sin 345
(4) tan 195

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  1. remember your standard angles and half-angle formulas, then
    sin225 = sin(180+45) = -sin45
    cos195 = cos(180+15) = -cos15 = -cos(30/2)
    sin345 = sin(360-15) = -sin15
    tan195 = tan(180+15) = tan15 = tan(30/2)

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  2. Aye

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