天津出口退税:高一数学

来源:百度文库 编辑:查人人中国名人网 时间:2024/05/02 16:54:39
cos(24°-x)cos(16°+x)-sin(24°-x)sin(16°+x)+sin10°-cos20°

cos(24°-x)cos(16°+x)-sin(24°-x)sin(16°+x)+sin10°-cos20°
=cos(24°-x+16°+x)+sin10°-cos20°
=cos40°+sin10°-cos20°
=cos(30°+10°)+sin10°-cos(30°-10°)
=cos10°cos30°-sin10°sin30°+sin10°-cos10°cos30°-sin10°sin30°
=sin10°-2sin10°sin30°
=0