cos80乘cos35+cos10乘cos55(数字均为度数) 1.sin12分之π+cos十二分之π等于 (求解法)2.cos105度+sin195(度)

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cos80乘cos35+cos10乘cos55(数字均为度数) 1.sin12分之π+cos十二分之π等于 (求解法)2.cos105度+sin195(度)

cos80乘cos35+cos10乘cos55(数字均为度数) 1.sin12分之π+cos十二分之π等于 (求解法)2.cos105度+sin195(度)
cos80乘cos35+cos10乘cos55(数字均为度数)
1.sin12分之π+cos十二分之π等于 (求解法)2.cos105度+sin195(度)

cos80乘cos35+cos10乘cos55(数字均为度数) 1.sin12分之π+cos十二分之π等于 (求解法)2.cos105度+sin195(度)
cos80cos35+cos10cos55
=sin10cos35+cos10sin35
=sin(10+35)=sin45
=√2/2
sinπ/12+cosπ/12
=√2(√2/2sinπ/12+√2/2cosπ/12)
=√2sin(π/4+π/12)
=√2sinπ/3
=√6/2
cos105+sin195
=cos105+sin(90+105)
=cos105+cos105
=2cos105
=2cos(60+45)
=2(cos60cos45-sin60sin45)
=2(1/2*√2/2-√3/2*√2/2)
=(√2-√6)/2
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