算法没问题,按你的代码,调整了一下
Private Sub Command1_Click()
Dim a!,b!,c!
a = Val(InputBox("请输入a"))
b = Val(InputBox("请输入b"))
c = Val(InputBox("请输入c"))
If a + b > c And a + c > b And b + c > a Then
Print a,b,c,"能构成三角形"
If a = b Or b = c Or a = c Then Print "等腰三角形"
If a = b = c Then Print "等边三角形"
Else
Print a,b,c,"不能构成三角形"
End If
End Sub