Vincen wrote: ↑Fri May 28, 2021 7:38 am
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
Answer:
E
Source: GMAT Prep
Let x be the length (and width) of the square screen with diagonal 21
The area of the large screen will be x²
Let y be the length (and width) of the square screen with diagonal 19
The area of the small screen will be y²
Our goal is to find the value of x² - y²
Large TV: If we examine the right triangle created by 2 sides (both with length x) and the diagonal, we can apply the Pythagorean Theorem to get x² + x² = 21²
When we simplify this, we get 2x² = 441, which means x² = 441/2
Small TV: If we examine the right triangle created by 2 sides (both with length y) and the diagonal, we can apply the Pythagorean Theorem to get y² + y² = 19²
When we simplify this, we get 2y² = 361, which means y² = 361/2
We can now find the value of x² - y²
We get x² - y² = 441/2 - 361/2 = 80/2 = 40
Answer: E
Cheers,
Brent
