I'm helping a teacher develop some geometry activities (pattern block designs), but am running into some quirky behavior. I'm using the Basic Shapes (US Units) with Visio 2010 (typical install - no customizations).

When I drag a 1-inch square onto the page, its corners fit perfectly into the major gridlines. Everything looks good. Then if I drag a triangle out onto the page, the triangle is a bit too wide, even though the shape geometry SAYS it's 1 inch.

(Apparently I can't post images yet, so sorry, no screenshot)

If I resize the triangle to fit the square, it says it's 0.875 inches. The resulting printed shapes match up to this expectation - the 0.875"-wide triangle prints as 1" wide.

I suppose I can just use 0.875" triangles and remember that they're really 1", but is there something else going on here? Or is it just a bad shape? 

The shape is an equilateral triangle, with its height set to 1.5 inches. If you rotate the shape you will see this.

If you don't want an equilateral triangle then you can edit the shape, open the shape's shapesheet and edit the geometry section.

set Line 1 X -> Width*1

and Line 3 X -> Width*0

Oh yes, and do similare to the connection points