cos75°*cos15°-sin225°*sin15°的值为?
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/09/01 12:12:58
cos75°*cos15°-sin225°*sin15°的值为?
cos75°*cos15°-sin225°*sin15°
= cos75°*cos15°- sin(180°+ 45°)*sin15°
= cos75°*cos15°+ sin45°*sin15°
= (√6-√2)/4 × (√6+√2)/4 + √2/2 × (√6-√2)/4
= (6-2)/16 + √2/2 × (√6-√2)/4
= 1/4 + √2/2 × (√6-√2)/4
= 1/4 + (√12-√4)/8
= 1/4 + (2√3-2)/8
= 1/4 + (√3-1)/4
= √3/4
= cos75°*cos15°- sin(180°+ 45°)*sin15°
= cos75°*cos15°+ sin45°*sin15°
= (√6-√2)/4 × (√6+√2)/4 + √2/2 × (√6-√2)/4
= (6-2)/16 + √2/2 × (√6-√2)/4
= 1/4 + √2/2 × (√6-√2)/4
= 1/4 + (√12-√4)/8
= 1/4 + (2√3-2)/8
= 1/4 + (√3-1)/4
= √3/4
cos75°cos15°+sin75°sin15°的值为( )
(cos15°-cos75°)(sin75°+sin15°)=?
sin15°,sin75°,sin105°,cos15°,cos75°,cos105°用公式算值为多少
tan15°、tan75°sin15°、sin75°、cos15°cos75°具体数值
求cos25°cos15°-cos75°sin15°解答过程
(cos15°-cos75°)(sin75°+sin15°)怎么化简?
tan15°+cos15°/sin15°的值 求详解
求sin15°+tan30°cos15°的值
计算tan15°+cos15°/cos75°
求sin15,sin75,cos15,cos75,tan15,tan75的准确值
sin75度cos15度-cos75度sin15度的值为
tan15° sin15° cos15° tan75° cos75° sin75° tan105° cos105° si