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sin(`°)等于多少

解 sin(-60) =-sin60 =-√3/2

sin(b+90°)=cosb

解:因为.arcsin0.5=30°+2kπ, k属于整数 所以, sin(30°+2kπ)=0.5, k属于整数

sin(10°) = 0.17364817766693

sin(-855°)=sin225°=-sin45°≈-0.707

解:∵sin36°=cos54°即sin(2×18°)=cos(3×18°)2sin18°cos18°=4(cos18°)^3-3cos18°∵cos18°≠0∴2sin18°=4(cos18°)^2-3整理得4(sin18°)^2+2sin18°-1=0解得sin18°=(根号5-1)/4

sin(-2010°) =sin(-360°×5-210°) =sin(-210°) =sin(-360°+150°) =sin150° =sin(180°-30°) =sin30° =1/2

同理: cos15° =cos(45°-30°) =cos45°cos30°+sin45°sin30° =(√2/2)(√3/2)+(√2/2)(1/2) =(√6+√2)/4

sinA=-3/4 A=arcsin(-3/4)=-48.6° 或A=360-48.6=311.4°

sin23°≈0.39 对于这种不是特殊角的,求正弦值的话,一般都采用查表法。

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