求cos15°-tan15°/cos15°+sin15°
问题描述：
求cos15°-tan15°/cos15°+sin15°
答
sin30°=sin2*15 ° =2sin15° cos15° =1/2 sin15° cos15° =1/4
cos30°=cos2*15°=2(cos15°)^2-1=√3/2 (cos15°)^2=√3/4+1/2
tan15° =sin15° cos15° /cos15° cos15° =1/(√3+2)=2-√3
cos15°-tan15°/cos15°+sin15°
=(cos15° cos15°-tan15 ° +sin15° cos15°)/cos15 °
=5(3√3-5)/2
答
是 (cos 15°-tan 15°) / (cos 15°+sin 15°) 吗?= = = = = = = = =因为 sin 15°=sin (45°-30°) =sin 45°cos 30°-cos 45°sin 30° =(根号2) /2 *(根号3) /2 -(...