（tan5°-cot5°）×cos70°1+sin70°=_．
问题描述：
（tan5°-cot5°）×
=______． cos70° 1+sin70°
答
（tan5°-cot5°）×cos70°1+sin70°=（sin5°cos5°-cos5°sin5°）•sin20°1+cos20°=sin25°−cos25°sin5°cos5°•sin20°1+cos20°=−cos10°12sin10°•2sin10°cos10°2cos210°=-2，故答案为：-2．...