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The area of a rectangle and the square of its perimeter are in the ratio 1:251:25. Then the lengths of the shorter and longer sides of the rectangle are in the ratio

Solution

✅ Correct Option: 1

We're told that for a rectangle:

Area : (Perimeter)² = 1 : 25

We need to find the ratio of the shorter side to the longer side.


Let's call the sides of the rectangle aa and bb.

Area of rectangle = a×ba \times b

Perimeter of rectangle = 2(a+b)2(a + b)

Square of perimeter = [2(a+b)]2[2(a + b)]^2


From the given ratio: Area : (Perimeter)² = 1 : 25

This means: Area(Perimeter)2=125\frac{\text{Area}}{(\text{Perimeter})^2} = \frac{1}{25}

ab[2(a+b)]2=125\frac{ab}{[2(a + b)]^2} = \frac{1}{25}


25ab=[2(a+b)]225ab = [2(a + b)]^2

25ab=4(a+b)225ab = 4(a + b)^2

25ab=4(a2+2ab+b2)25ab = 4(a^2 + 2ab + b^2)

25ab=4a2+8ab+4b225ab = 4a^2 + 8ab + 4b^2

25ab−8ab=4a2+4b225ab - 8ab = 4a^2 + 4b^2

17ab=4(a2+b2)17ab = 4(a^2 + b^2)


Dividing both sides by abab:

17=4(a2+b2)ab17 = \frac{4(a^2 + b^2)}{ab}

17=4(ab+ba)17 = 4\left(\frac{a}{b} + \frac{b}{a}\right)

Let r=abr = \frac{a}{b} (ratio of one side to the other):

17=4(r+1r)17 = 4\left(r + \frac{1}{r}\right)

174=r+1r\frac{17}{4} = r + \frac{1}{r}

4.25=r+1r4.25 = r + \frac{1}{r}

This gives us: r2−4.25r+1=0r^2 - 4.25r + 1 = 0

Using the quadratic formula: r=4r = 4 or r=14r = \frac{1}{4}


Since we want the ratio of shorter : longer side:

If r=4r = 4, then one side is 4 times the other, so shorter : longer = 1 : 4

If r=14r = \frac{1}{4}, then one side is 14\frac{1}{4} of the other, so shorter : longer = 1 : 4


Therefore, the ratio of shorter to longer sides is 1 : 4

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