Question

sin 420°cos 390° - cos(-300°) sin(-330°)
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Answer 1

Step-by-step explanation:

Sin 420 = sin (360+60) = sin 60 = √3/2

cos 390 = cos (360+30) = cos 30 = √3/2

cos (-300) = cos 300 = cos(360 - 60) = cos 60 = 1/2

sin (-330) = sin (360 + (-330) ) = sin 30 = 1/2

LHS = √3/2 * √3/2 + 1/2 * 1/2 = 1