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数学
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sin78°cos18°-sin12°sin162°=
人气:418 ℃ 时间:2020-07-12 06:16:50
解答
原式=sin(90°-12°)cos18°-sin12°sin(180°-18°)
=cos12°cos18°-sin12°sin18°
=cos(12°+18°)
=cos30°
=√3/2
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