Bunuel
In two equilateral parallelograms, X and Y, the sum of the lengths of the diagonals of X is equal to the sum of the lengths of the diagonals of Y. In X, the length of the longer diagonal is 20 more than the length of the shorter diagonal. In Y, the length of the longer diagonal is 8 more than the length of the shorter diagonal. What is the area of Y minus the area of X?
A. 336
B. 168
C. 84
D. 42
E. 0
Equilateral parallelogram indicates that the quadrilateral is a Rhombus.
Area of Rhombus =\(\frac{ 1}{2}\) * product of diagonals
GivenParallelogram : X
- Shorter Side: x
- Longer Side: x+20
Parallelogram : Y
- Shorter Side: y
- Longer Side: y+8
The sum of the lengths of the diagonals of X is equal to the sum of the lengths of the diagonals of Y
x + x + 20 = y + y + 8
x = y - 6
Question\(\frac{1}{2} * y * (y+8) - 1/2 * x * (x+20)\)
Substituting x in terms of y
\([\frac{1}{2 }* y * (y+8)] - [\frac{1}{2} * (y-6) * (y + 14)]\)
\(\frac{1}{2}[y^2 + 8y - y^2 - 8y + (14*6)]\\
\)
\(14 * 3 = 42\)
Option D