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Question

A steel plate is in the shape of a right triangle. The lengths of the legs are in the ratio 5:12. If the hypotenuse is 13 m, what is the area?

This question was previously asked in
SSC CGL 2025 Tier 1 Question Paper (25-Sep-2025) (Shift 3)
The correct answer is
$30 \text{ m}^2$

Calculating Right Triangle Area Using Leg Ratio and Hypotenuse

The problem asks for the area of a right triangle where the lengths of the two legs are in the ratio 5:12, and the hypotenuse is 13 m.

Finding Leg Lengths

Let the lengths of the legs be $5x$ and $12x$, where $x$ is a constant multiplier. According to the Pythagorean theorem, for a right triangle with legs $a$ and $b$ and hypotenuse $c$, we have $a^2 + b^2 = c^2$. Applying this to our triangle:

$ (5x)^2 + (12x)^2 = 13^2 $

Simplify the equation:

$ 25x^2 + 144x^2 = 169 $

Combine the terms:

$ 169x^2 = 169 $

Solve for $x^2$:

$ x^2 = \frac{169}{169} $ $ x^2 = 1 $

Solve for $x$. Since length must be positive, we take the positive square root:

$ x = \sqrt{1} $ $ x = 1 $

Now, find the actual lengths of the legs:

  • Leg 1: $5x = 5 \times 1 = 5 \text{ m}$
  • Leg 2: $12x = 12 \times 1 = 12 \text{ m}$

Calculating the Area

The area of a right triangle is calculated using the formula: Area = $\frac{1}{2} \times \text{base} \times \text{height}$. The legs of the right triangle serve as the base and height.

$ \text{Area} = \frac{1}{2} \times 5 \text{ m} \times 12 \text{ m} $

$ \text{Area} = \frac{1}{2} \times 60 \text{ m}^2 $

$ \text{Area} = 30 \text{ m}^2 $

Therefore, the area of the steel plate is $30 \text{ m}^2$.

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Similar Questions

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Important Questions from 2-D Mensuration

  1. The sides of a rectangular field are 169 m and 154 m long. Its area is equal to the area of a circular field. What is the circumference (in m) of the circular field? Take $\pi = \frac{22}{7}$
  2. Find the area of a sector with a central angle of 150° in a circle with a radius of 12 cm.
  3. The area of a square is $2304$ cm$^2$. Its perimeter is equal to the perimeter of a regular hexagon. What is the area (in cm$^2$) of the hexagon?
  4. Calculate the area of the triangle whose sides are 8 cm, 9 cm and 13 cm. (Rounded up to two decimal places)

  5. The length of a rectangular pitch is 30 m more than its breadth. Its area is $18,271$ m$^{2}$. Its breadth (in m) is:
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