# Thread: Center object snap.

1. ## Center object snap.

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Ok I'm taking this online autocad class. I was doing some chapter questions and one of them was this one.

What types of objects does the Center object snap work with?

a) Circles and lines.
b) Circle, arcs, and rectangles.
c) Circle, arcs, and lines.
d) Circles and arcs.

It turns out the answer is d. I thought it was c. Why is d the answer don't lines have center object snap?

2. Lines have a midpoint snap not a center object snap.

3. Originally Posted by warbirt
Lines have a midpoint snap not a center object snap.

That is the same thing. The midpoint is the center point. What the hell is that? It's like a trick question.

4. Only circles, arcs and ellipses have center object snaps. I guess the question did not mention the ellipse since it's center object snap is not a true center point.

Midpoint object snaps are not centers of anything.

In the case of the ellipse, it is more of a geographic center but it is there.

The ellipse is the only one that cannot be drawn around its own center object snap point, which depending on the ellipse's proportions, is only coincidental with any of the arc center points used to make up the ellipse.

I suppose AutoDesk gave the Ellipse a center object snap because it is handy.

5. essentially they are the same thing but the definition of a midpoint in mathematics relates to a line and defintion of center relates to a circle or arc.

Also an arc is a line and therfore object snap will allow you to snap to the midpoint of the arc line (shown with a triangle) as well as the center point (shown with a circle).

6. Originally Posted by prime333
That is the same thing. The midpoint is the center point. What the hell is that? It's like a trick question.
Not true. Lines do not have a center in the true geometric definition. W have merely come to refer to the middle of things as the center. The middle or mid-point is not the center.

7. I understand, but the semantics in this question are retarded.

8. It can be said that any geometric shape whether closed or not can have a center, but it is only conceptual, like a square for instance, but a square cannot be drawn using the center point as any sort of guide.

To be a center, the point has to be equidistant from all points on the surrounding perimeter.

A square's center is only equidistant from many sets of four points along the perimeter, with each set having a different distance.

9. Originally Posted by prime333
I understand, but the semantics in this question are retarded.
The semantics are perfect. The question is about center object snap points, of which there are three. Two of these snap points are referred to in the question. The question is not about whether any given object has a center.

The answer is "D" because those are the only two objects referred to which have center object snaps.

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You have to learn to speak "AutoCAD". Then everything is crystal clear

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