Last visit was: 20 Dec 2024, 08:55 It is currently 20 Dec 2024, 08:55

Close

GRE Prep Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GRE score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel
Verbal Expert
Joined: 18 Apr 2015
Posts: 30420
Own Kudos [?]: 36778 [0]
Given Kudos: 26092
Send PM
Most Helpful Community Reply
Manager
Manager
Joined: 11 Nov 2023
Posts: 207
Own Kudos [?]: 242 [1]
Given Kudos: 76
WE:Business Development (Advertising and PR)
Send PM
General Discussion
Intern
Intern
Joined: 07 Feb 2024
Posts: 1
Own Kudos [?]: 0 [0]
Given Kudos: 8
Send PM
Verbal Expert
Joined: 18 Apr 2015
Posts: 30420
Own Kudos [?]: 36778 [0]
Given Kudos: 26092
Send PM
The area of a regular octagon [#permalink]
Expert Reply
OE



This problem asks you to compare the area of an octagon to the area of a square. First, the simpler Quantity B is calculated using the formula for the area of a square:

Area = side^2 = \(8^2 = 64\)

Next, calculate Quantity A.

The easiest way to calculate the area of a regular octagon only knowing the length of a side is to sketch out the octagon and divide into regions whose areas are easy to calculate.

The octagon is divided into,(1) a square with area 4 x 4, (2) 4 rectangles each with an area of 4 x A, and (3) 4 triangles each with an area \(\frac{1}{2}A^2\).

From these pieces we can derive an area formula as follows:

Area of Octagon \(= 4^2 + 4 * \frac{1}{2} A^2 + 4 * 4 * A\)

A can be calculated using the Pythagorean Theorem:

\(4^2 = A^2 + A^2\)
\(16 = 2A^2\)
\(4 = A\) \(\sqrt{2}\)
\(A= \dfrac{4}{\sqrt{2}}=2 \sqrt{2}\)

Now substitute value for A into the original Area Formula:

Area of Octagon \(= 4^2 + 2 · (2\sqrt{2})^2 + 4 · 4 · 2\sqrt{2}\)

\(16 + 16 + 32\sqrt{2} = 77.25\)

77.25 is greater than 64, therefore Quantity A is greater than Quantity B. The correct answer choice is A.
Prep Club for GRE Bot
The area of a regular octagon [#permalink]
Moderators:
GRE Instructor
88 posts
GRE Forum Moderator
37 posts
Moderator
1115 posts
GRE Instructor
234 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne