代码如下：

Private Sub Command1_Click()

Dim a, g, s, z, x, d, l, y, f, m, dd, gc As Single
g = Val(Text1.Text)
y = Val(Text2.Text)
s = Val(Text3.Text)
z = Val(Text4.Text)
x = Val(Text5.Text)
d = Val(Text6.Text)
f = Val(Text7.Text)
m = Val(Text8.Text)

l = s - x
Text9.Text = Val(Format(l, "0.0000"))
d = d / 180
f = f / 60 / 180
m = m / 3600 / 180
a = (d + f + m) * 3.1415926
dd = 100 * l * Sin(a) * Sin(a)
gc = dd * Tan(a) + y - z + g
Text10.Text = Val(Format(a, "0.0000"))
Text11.Text = Val(Format(dd, "0.0000000000"))
Text12.Text = Val(Format(gc, "0.0000"))

End Sub

最后的结果GC的答案与实际不符合

不知道，我错在哪里？

请指教，谢谢！

其余计算正确，就是：gc = dd * Tan(a) + y - z + g

计算有问题，不知道错在哪？

代码上面有误。应该如下：
Dim a, g, s, z, x, d, l, y, f, m, dd, gc As Single
g = Val(Text1.Text)
y = Val(Text2.Text)
s = Val(Text3.Text)
z = Val(Text4.Text)
x = Val(Text5.Text)
d = Val(Text6.Text)
f = Val(Text7.Text)
m = Val(Text8.Text)

l = s - x
Text9.Text = Val(Format(l, "0.0000"))
d = d / 180
f = f / 60 / 180
m = m / 3600 / 180
a = (d + f + m) * 3.1415926
dd = 100 * l * Cos(a) * Cos(a)
gc = dd * Tan(a) + y - z + g
Text10.Text = Val(Format(a, "0.0000"))
Text11.Text = Val(Format(dd, "0.0000"))
Text12.Text = Val(Format(gc, "0.0000"))

为什么仅仅DD的计算有误呢？

而其他计算均正确呢？

找到了！
应该为：bb = 3.1415926 / 2 - (d + f + m) * 3.1415926

结果正确！

谢谢！