14.1/2sin(π/8×2)=1/2sinπ/4=根号2/4
15.原式=(tan81°-tan36°)/(1+tan81°tan36°)
=tan(81°-36°)
=tan45°
=1
这2题,最好截图给我看看啦，电脑写的不怎么清晰
14.1/2sin(π/8×2)=1/2sinπ/4=根号2/4
15.原式=(tan81°-tan36°)/(1+tan81°tan36°)
=tan(81°-36°)
=tan45°
=1