问题
填空题
请在括号内填写一个整数,使得等式
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答案
∵cos50°+
sin50°=2(3
cos50°+1 2
sin50°)3 2
=2(sin30°cos50°+cos30°sin50°)=2sin(sin30°+50°)=2sin80°,
∴
+1 sin50°
=3 cos50°
=cos50°+
sin50°3 sin50°cos50°
=2sin80°
sin100°1 2
=4,2sin80°
sin80°1 2
故当括号填的整数为1时,满足题意,
故答案为:1