Which expression is equivalent to (6x2y - Zx-y2 - 7y + 19) - (-8xy + 14xy – 13x+y2 - 10)?

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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.

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