GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 20 Jun 2018, 23:26

### GMAT 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

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

Practice
Pays

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# The size of a television screen is given as the length of

Author Message
TAGS:

### Hide Tags

Manager
Joined: 16 Feb 2012
Posts: 200
Concentration: Finance, Economics
The size of a television screen is given as the length of [#permalink]

### Show Tags

Updated on: 08 Jul 2012, 05:06
2
00:00

Difficulty:

35% (medium)

Question Stats:

71% (01:13) correct 29% (01:31) wrong based on 182 sessions

### HideShow timer Statistics

The size of a television screen is given as the length of the screen's diagonal. If the screens were flat, then the area of a square 21-inch screen would be how many square inches greater than the area of a square 19-inch screen?

A. 2
B. 4
C. 16
D. 38
E. 40

_________________

Kudos if you like the post!

Failing to plan is planning to fail.

Originally posted by Stiv on 08 Jul 2012, 04:45.
Last edited by Bunuel on 08 Jul 2012, 05:06, edited 1 time in total.
Edited the question.
Math Expert
Joined: 02 Sep 2009
Posts: 46217
Re: The size of a television screen is given as the length of [#permalink]

### Show Tags

08 Jul 2012, 05:07
4
Stiv wrote:
The size of a television screen is given as the length of the screen's diagonal. If the screens were flat, then the area of a square 21-inch screen would be how many square inches greater than the area of a square 19-inch screen?

A. 2
B. 4
C. 16
D. 38
E. 40

$$d_1=21$$ and $$d_2=19$$ --> $$area_{square}=\frac{d^2}{2}$$ --> $$area_1-area_2=\frac{(d_1)^2}{2}-\frac{(d_2)^2}{2}=\frac{21^2-19^2}{2}=\frac{(21-19)(21+19)}{2}=\frac{2*40}{2}=40$$

_________________
Intern
Joined: 22 Jun 2011
Posts: 5
Re: The size of a television screen is given as the length of [#permalink]

### Show Tags

08 Jul 2012, 10:05
Bunuel wrote:
Stiv wrote:
The size of a television screen is given as the length of the screen's diagonal. If the screens were flat, then the area of a square 21-inch screen would be how many square inches greater than the area of a square 19-inch screen?

A. 2
B. 4
C. 16
D. 38
E. 40

$$d_1=21$$ and $$d_2=19$$ --> $$area_{square}=\frac{d^2}{2}$$ --> $$area_1-area_2=\frac{(d_1)^2}{2}-\frac{(d_2)^2}{2}=\frac{21^2-19^2}{2}=\frac{(21-19)(21+19)}{2}=\frac{2*40}{2}=40$$

Just to refresh my understanding, how is the $$area_{square}=\frac{d^2}{2}$$

The side x side is simple enough. Given that a square is essentially 2 isoceles triangles, I was going with 21=$$x\sqrt{2}$$

That's where I got stuck. But I still don't get your formula...
Math Expert
Joined: 02 Sep 2009
Posts: 46217
Re: The size of a television screen is given as the length of [#permalink]

### Show Tags

08 Jul 2012, 10:08
1
manavecplan wrote:
Bunuel wrote:
Stiv wrote:
The size of a television screen is given as the length of the screen's diagonal. If the screens were flat, then the area of a square 21-inch screen would be how many square inches greater than the area of a square 19-inch screen?

A. 2
B. 4
C. 16
D. 38
E. 40

$$d_1=21$$ and $$d_2=19$$ --> $$area_{square}=\frac{d^2}{2}$$ --> $$area_1-area_2=\frac{(d_1)^2}{2}-\frac{(d_2)^2}{2}=\frac{21^2-19^2}{2}=\frac{(21-19)(21+19)}{2}=\frac{2*40}{2}=40$$

Just to refresh my understanding, how is the $$area_{square}=\frac{d^2}{2}$$

The side x side is simple enough. Given that a square is essentially 2 isoceles triangles, I was going with 21=$$x\sqrt{2}$$

That's where I got stuck. But I still don't get your formula...

The area of a square is $$side^2$$, but since here the length of the diagonal is given, then it's better to use another formula $$area_{square}=\frac{diagonal^2}{2}$$.
_________________
Senior Manager
Joined: 13 May 2013
Posts: 430
Re: The size of a television screen is given as the length of [#permalink]

### Show Tags

12 Dec 2013, 12:43
1
The size of a television screen is given as the length of the screen's diagonal. If the screens were flat, then the area of a square 21-inch screen would be how many square inches greater than the area of a square 19-inch screen?

A. 2
B. 4
C. 16
D. 38
E. 40

We're dealing with squares here. When you take the diagonal of a square it creates two isosceles triangles with a ratio of x: x: x√2. Because the hypotenuse is 21 inches it is equal to x√2. To find the length of the legs, we set 21 = x√2. x = 21/√2
To find the area we square 21/√2 which equals 441/2. Similarly, for the 19 inch screen we follow the same steps. We find that the legs of the triangle (or the sides of the square screen) are 19/√2 inches. To find the area we square this to get 361/2. Finally, subtract 361/2 from 441/2 to get 80/2 = 40.

E
Intern
Joined: 20 Jun 2016
Posts: 5
Location: United States (MA)
Concentration: Finance, Technology
Schools: Carroll '20
GMAT 1: 650 Q40 V38
GPA: 3.25
The size of a television screen is given as the length of [#permalink]

### Show Tags

13 Nov 2017, 23:16
manavecplan wrote:
Bunuel wrote:
Stiv wrote:
The size of a television screen is given as the length of the screen's diagonal. If the screens were flat, then the area of a square 21-inch screen would be how many square inches greater than the area of a square 19-inch screen?

A. 2
B. 4
C. 16
D. 38
E. 40

$$d_1=21$$ and $$d_2=19$$ --> $$area_{square}=\frac{d^2}{2}$$ --> $$area_1-area_2=\frac{(d_1)^2}{2}-\frac{(d_2)^2}{2}=\frac{21^2-19^2}{2}=\frac{(21-19)(21+19)}{2}=\frac{2*40}{2}=40$$

Just to refresh my understanding, how is the $$area_{square}=\frac{d^2}{2}$$

The side x side is simple enough. Given that a square is essentially 2 isoceles triangles, I was going with 21=$$x\sqrt{2}$$

That's where I got stuck. But I still don't get your formula...

I had to try it out myself to understand the formula. As you mentioned with the diagonal, we calculate the length of each side = $$\frac{21}{\sqrt{2}}$$ = x
Area of a Square is $$(Side^2) = (\frac{21}{\sqrt{2}} * \frac{21}{\sqrt{2}}) = \frac{21^2}{2} = \frac{diagonal^2}{2}$$
The size of a television screen is given as the length of   [#permalink] 13 Nov 2017, 23:16
Display posts from previous: Sort by