The width of a rectangle is 2 less than twice its length. If the area of the rectangle is 51 cm , what is the length of the diagonal?

Answer 1

Let L = length of the rectangle

Then W = 2L - 2

Find the value of L based on A = LW

L(2L - 2) = 51

2L²- 2L - 51 = 0

Use the quadratic formula to find L (the trinomial does not factor). Use the positive result since L cannot be negative.

Now use the Pythagorean Theorem to find the length of the diagonal.

D² = L² + (2L-2)²

Since L is irrational this gets a bit messy.

Once you have tried all that, check here to confirm:

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