sin﹙-1320°﹚cos1410°+cos﹙1 - 知识问答

sin﹙-1320°﹚cos1410°+cos﹙135°﹚×sin﹙-30°﹚+tan765° 对即奖!

1个回答

原式=sin(-4×360°+120°)×cos(4×360°-30°)+cos(180°-45°)×(-sin30°)+tan(2×360°+45°)
=sin120°×cos30°+(-cos45°)×(-sin30°)+tan45°
=sin(180°-60°)×cos30°+cos45°×sin30°+tan45°
=sin60°×cos30°+cos45°×sin30°+tan45°
=√3/2×√3/2+√2/2×1/2+1
=3/4+√2/4+1
=(7+√2)/4

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