# NCERT Class 8 Mathematics Solutions: Chapter 11 –Mensuration Exercise 11.2 Part 6

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1. Top surface of a raised platform is in the shape of a regular octagon as shown in the figure. Find the area of the octagonal surface.

Answer:

Given:

Octagon having eight equal sides, each .

Construction:

Divided the octagon in figures, two trapeziums whose parallel and perpendicular sides are respectively and third figure is rectangle having length and breadth respectively.

Now,

Area of two trapeziums

And

Area of rectangle

Total area of octagon