Converse, Inverse, contraposative?

Question

What is the converse, inverse, and contrapositive of: The sum of the angle of a triangle is 180 degrees.

Answer 1

converse, inverse, and contrapositive apply to conditional statements. The statement you've given is not conditional. You could make it one by saying something like,
If a polygon is a triangle, then the sum of its angles is 180. (if T then S)

In that case, the converse would be,
If the sum of the angles of a polygon is 180, the polygon is a triangle. (if S then T)

The inverse would be,
If a polygon is a triangle, the sum of its angles is NOT 180. (if T then not S)

And the contrapositive would be,
If the sum of the angles of a polygon is not 180, the polygon is not a triangle. (if not S then not T)

Answer 2

I need to restate your original statement as a proposition:

Original

If the sum of the interior angles of a polygon is 180 degrees, then the polygon is a triangle.

Converse

If the polygon is a triangle then the sum of the interior angles is 180 degrees.

Inverse

If the sum of the interior angles of a polygon is Not 180 degrees, then the polygon is Not a triangle.

Contrapostive

If the polygon is Not a triangle, then the sum of the interior angles is Not 180 degrees.

Answer 3

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