化简sin6°cos24°sin78°cos48°
问题描述：
化简sin6°cos24°sin78°cos48°
答
sin6°cos24°sin78°cos48°=cos6°sin6°cos24°sin78°cos48°/cos6°
=sin12°cos12°cos24°cos48°/2cos6°
=sin24°cos24°cos48°/4cos6°
=sin48°cos48°/8cos6°
=sin96°/16cos6°
=cos6°/16cos6°
=1/16
(注：sin78°=cos12° sin96°=sin[90°-（-6°)]=cos(-6°)=cos6° )