Question 1122020: Pease help me solve this equation:
Find the dimensions of a rectangle whose area is 247 cm2 and whose perimeter is 64 cm. (Enter your answers as a comma-separated list.)
Found 2 solutions by josgarithmetic, ikleyn: Answer by josgarithmetic(39617) (Show Source): Answer by ikleyn(52782) (Show Source):
You can put this solution on YOUR website! .
Let me show you a quick, elegant and unexpected method of solving such problems.
You are given that the perimeter of the rectangle is 64 cm; hence, the sum of the length and the width is one half of that:
x + y = 32, where x is the length, and y is the width.
Then the average of the length and the width is one half of 32, i.e. 16.
It is clear that the values of x and y are remoted at the same value/distance "u" from 16, so we can write
x = 16 + u,
y = 16 - u.
Then the area is xy = (16+u)*(16-u) = , and it is equal to 247, according to the condition.
Hence, = 247, which gives = 256 - 247 = 9, and then u = = 3.
Thus the length is x = 16 + u = 16 + 3 = 19,
and the width is x = 16 - u = 16 - 3 = 13.
Answer. The dimensions of the rectangle are 13 cm and 19 cm.
Solved.
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See the lesson
- Three methods to find the dimensions of a rectangle when its perimeter and the area are given
in this site.
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