玄缙
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2sin50°+cos10°(1+根号3tan10°)/根号下1+2sin50°cos50°
=(2sin50°+cos10°(1+√3*tan10°))/√(sin^2 50°+2sin50°cos50°+cos^2 50°)
=(2sin50°+cos10°+√3sin10°)/√√(sin50°+cos50°)^2
=(2sin50°+2sin(10°+30°))/(sin50°+cos50°)
=2(sin50°+sin40°)/(sin50°+cos50°)
=2(sin50°+cos50°)/(sin50°+cos50°)
=2
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2(sin50°+sin40°)/(sin50°+cos50°) 这一步怎么来的?没看懂!
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玄缙
cos10°+√3sin10° =2(1/2cos10°+√3/2sin10°) =2(sin30°cos10°+cos30°sin10°) =2sin(30°+10°) =2sin40°