I am using the following code to draw a 1 mile buffer around a polygon. When I measure the distance from the edge of the polygon to the buffer, its not accurate. North and South are fine, but East and West are off.
Dim pMxDoc As IMxDocument
Dim pActiveView As IActiveView
Dim pGraphicsContainer As IGraphicsContainer
Dim pEnumFeature As IEnumFeature
Dim pFeature As IFeature
Dim pTopoOp As ITopologicalOperator
Dim pElement As IElement
Dim strBufferDistance As String
Set pMxDoc = Application.Document
Set pActiveView = pMxDoc.FocusMap
Set pGraphicsContainer = pMxDoc.FocusMap
'Verify there is a feature selection
If pMxDoc.FocusMap.SelectionCount = 0 Then Exit Sub
'Get a buffer distance from the user
strBufferDistance = InputBox("Enter Distance:", "Buffer")
If strBufferDistance = "" Or Not IsNumeric(strBufferDistance) Then Exit Sub
'Buffer all the selected features by the BufferDistance
'and create a new polygon element from each result
Set pEnumFeature = pMxDoc.FocusMap.FeatureSelection
pEnumFeature.Reset
Set pFeature = pEnumFeature.Next
Do While Not pFeature Is Nothing
Set pTopoOp = pFeature.Shape
Set pElement = New PolygonElement
pElement.Geometry = pTopoOp.Buffer(CInt(strBufferDistance))
pGraphicsContainer.AddElement pElement, 0
Set pFeature = pEnumFeature.Next
Loop
'Redraw the graphics