cos80乘cos35+cos10乘cos55(数字均为度数)
问题描述:
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)
答
cos80cos35+cos10cos55=sin10cos35+cos10sin35=sin(10+35)=sin45=√2/2sinπ/12+cosπ/12=√2(√2/2sinπ/12+√2/2cosπ/12)=√2sin(π/4+π/12)=√2sinπ/3=√6/2cos105+sin195=cos105+sin(90+105)=cos105+cos105...