tan60°+9tan30°-½tan45°+sin30°= cos 60°+√2/2sin45°+tan30°·cos30°=sin60°·cos60°+sin45°·cos45°-sin30°·cos30°=救急!
来源:学生作业帮助网 编辑:作业帮 时间:2024/08/16 06:23:25
![tan60°+9tan30°-½tan45°+sin30°= cos 60°+√2/2sin45°+tan30°·cos30°=sin60°·cos60°+sin45°·cos45°-sin30°·cos30°=救急!](/uploads/image/z/3703352-32-2.jpg?t=tan60%C2%B0%2B9tan30%C2%B0-%26%23189%3Btan45%C2%B0%2Bsin30%C2%B0%3D+cos+60%C2%B0%2B%E2%88%9A2%2F2sin45%C2%B0%2Btan30%C2%B0%C2%B7cos30%C2%B0%3Dsin60%C2%B0%C2%B7cos60%C2%B0%2Bsin45%C2%B0%C2%B7cos45%C2%B0-sin30%C2%B0%C2%B7cos30%C2%B0%3D%E6%95%91%E6%80%A5%21)
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tan60°+9tan30°-½tan45°+sin30°= cos 60°+√2/2sin45°+tan30°·cos30°=sin60°·cos60°+sin45°·cos45°-sin30°·cos30°=救急!
tan60°+9tan30°-½tan45°+sin30°= cos 60°+√2/2sin45°+tan30°·cos30°=
sin60°·cos60°+sin45°·cos45°-sin30°·cos30°=
救急!
tan60°+9tan30°-½tan45°+sin30°= cos 60°+√2/2sin45°+tan30°·cos30°=sin60°·cos60°+sin45°·cos45°-sin30°·cos30°=救急!
1、
tan60°=√3
tan30°=√3 /3
tan45°=1
sin30°=1/2
所以
原式
=√3 + 9* √3/3 -1/2 +1/2
=4√3
2、
cos60°= 1/2
sin45°=√2 /2
tan30° *cos30°=sin30°=1/2
所以
原式
=1/2 +√2 /2 *√2 /2 +1/2
=1/2 +1/2 +1/2
=3/2
3、
注意sina *cosa=0.5sin2a
所以
sin60°·cos60°+sin45°·cos45°-sin30°·cos30°
=0.5 *(sin120°+sin90° -sin60°)
=0.5 *(sin60°+1 -sin60°)
=0.5