Question

What is the area of the L - shaped hallway?

• A. $24$ square units
• B. $20$ square units
• C. $18$ square units

Answer 1

The correct option is B $20$ square units


Break down the composite figure into more familiar figures, find the area of each and then add them up.

In this case, there are two rectangles.



Area of rectangle $=$ length $\times$ breadth

Area of one rectangle
$=7\times 2=14$ square units

Area of second rectangle
$=5\times 2=10$ square units

Total area
$=14+10$
$=24$ square units

This is not the correct answer.

The reason is that both the rectangles are overlapping each other at certain parts.

That means the area of that part has been counted twice.


A small area of $2\times 2$ was counted twice.

Hence, the actual area $=24-(2\times 2)$

$=24-4=20$ square units