The perimeter of a square bulletin board is 280 cm how long is one of its side
2 answers:
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Answer:
Width = 2
Length = 5
Step-by-step explanation:
let A be the area of the rectangle
L be the length of the rectangle
w be the width of the rectangle
<u><em>Formula</em></u>: ‘<u><em>area of a rectangle</em></u>’
A = L × w
…………………………………………………
A = L × w
⇔ 10 = (w + 3) × w
⇔ 10 = w² + 3w
⇔ w² + 3w - 10 = 0
<u><em>Solving the quadratic equation</em></u> w² + 3w - 10 = 0 :
Δ = 3² - 4(1)(-10) = 9 - (-40) = 9 + 40 = 49
then √Δ = 7
-5 is not valid ,because w represents the width
which must be a positive number
Then w = 2
<u><em>Conclusion</em></u>:
Width = 2
Length = 2 + 3 = 5