直接贴出来吧:
圆锥体展开计算公式
大圆直径D=1200cm小圆直径d=10cm,高H'=40cm的圆台,
补充为圆锥体,圆锥体高H,母线长L,上半部分小圆锥体高H1,母线长L1,底面直径=d,
H:H1=(D/2) d/2)=D:d,
(H-H1):H1=(D-d):d,
H':H1=(1200-10):10
40:H1=119,
H1=40/119(cm),
H=H1+H'=40/119+40=40(120/119=4800/119(cm),
L1=√[H1²+(d/2)²]=√[(40/119)²+(10/2)²]=5.01(cm),
L=√[H²+(D/2)²]=√[(4800/119)²+(1200/2)²]=601.35(cm),
底面周长C=Dπ=1200π(cm)=展开图的大弧长,
圆心角α:360度=1200π:2πL,
α=360度*1200/(2*601.35)=359.1918度=359度11分31秒,
手工绘图方法:
先作α角,再以L为半径画圆弧,最后以L1为半径画弧. |