In plane geometry, what is the term for the distance around a two dimensional figure such as a rectangle, triangle or polygon?

Introduction / Context:
When studying plane figures such as rectangles, triangles and other polygons, we often measure two different things: how much space they cover and how long their boundary is. This question asks you to recall the specific geometric term used for the distance around a two dimensional figure.

Given Data / Assumptions:
- We are dealing with two dimensional shapes (figures in a plane).
- We want the total length of the boundary that encloses the figure.
- Common related terms include area and volume, which represent different concepts.

Concept / Approach:
The distance around a figure is called its perimeter. It is found by adding the lengths of all sides of the figure. For example, the perimeter of a rectangle is 2 times (length + breadth), while the perimeter of a triangle is the sum of its three side lengths. Area, by contrast, measures the amount of surface enclosed by the boundary, and volume applies to three dimensional solids.

Step-by-Step Solution:
Step 1: Recall that perimeter refers to the length of the outer boundary of a plane figure. Step 2: For a rectangle with sides length and breadth, perimeter = 2 * (length + breadth). Step 3: For a triangle, perimeter = side1 + side2 + side3. Step 4: The question simply asks for the term that describes this boundary length, not for a specific formula. Step 5: Therefore, the correct term is perimeter.

Verification / Alternative Check:
Consider a simple example of a rectangle that is 5 cm long and 3 cm wide. The perimeter is 2 * (5 + 3) = 16 cm. This 16 cm represents the total distance around the rectangle, which is exactly what is described in the question. The area, in contrast, would be 5 * 3 = 15 square centimeters, showing that area and perimeter are different measures.

Why Other Options Are Wrong:
Option A (Area) measures the amount of surface covered by a figure, not the distance around it.
Option C (Volume) applies to three dimensional objects, not flat figures, and measures space enclosed in three dimensions.
Option D (None of the above) is incorrect because perimeter is one of the given choices and it correctly describes the concept in the question.

Common Pitfalls:
Students sometimes confuse area and perimeter, especially when similar symbols or formulas are used. Always remember that area is measured in square units and refers to surface coverage, while perimeter is measured in linear units and refers to the boundary length.

Final Answer:
The distance around a two dimensional figure is called its Perimeter.