sin15°-cos15°/sin15°+cos15°的值?

网友回答

(sin15°-cos15)°/(sin15°+cos15°)
=(tan15°-1)/(tan15°+1)
=(tan15°-tan45°)/(tan45°tan15°+1)
=tan(15°-45°)
=-tan30°
=-√(3)/3
======以下答案可供参考======
供参考答案1:
sin15°-cos15°/sin15°+cos15°
=sin15°cos45°-cos15°sin45°/sin15°sin45°+cos15°cos45°
=sin(15-45°)/cos(15-45)
=-tan30°
=-根号3/3