原式=a2a-1-(a+1)=a2a-1-(a+1)(a-1)a-1
=a2-a2+1a-1
=1a-1,
故答案为:1a-1.
如果∠a=36°,那么∠a的余角等于( )
A.54°
B.64°
C.144°
D.134°
焊缝如果不在焊件的中性轴上,则焊后将会产生弯曲变形。( )