FTCE Professional Education Practice Exam

What defines a triangle?

1. A polygon with four sides

2. A polygon with three sides

3. A shape with at least one right angle

4. A figure with equal sides

The correct answer is: A polygon with three sides

A triangle is defined as a polygon with three sides. This definition encompasses the fundamental characteristics that distinguish triangles from other geometric shapes. Triangles are closed figures formed by three straight line segments connected end to end. The sum of the interior angles in any triangle is always 180 degrees, which is a crucial property that applies exclusively to this type of polygon. A polygon with four sides would be a quadrilateral, which is a different category of shape entirely. A shape with at least one right angle could refer to various types of polygons, including rectangles and certain types of triangles, but this does not define a triangle. Lastly, a figure with equal sides can describe an equilateral triangle but does not encompass all triangles, as triangles can also consist of sides of varying lengths. Thus, defining a triangle specifically as a polygon with three sides is precise and encompasses all variations of triangles, including isosceles, scalene, and equilateral.