( 7 x 5 + 4 x 3 − 2 x 2 + 12 x + 5 ) − ( 6 x 4 − 9 x 3 + x 2 − 3 ) Add/subtracts the polynomial

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since the cosine is the ratio of the adjacent side to the hypotenuse, you can see that cos 60° = ½. answer. according to the property of cofunctions (topic 3), sin 30° is equal to cos 60°. sin 30° = ½.