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Mathematics

The lengths of the sides of a right triangle are (2x − 1) m, (4x) m and (4x + 1) m, where x > 0. Find :

(i) the value of x,

(ii) the area of the triangle.

Quadratic Equations

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Answer

(i) Given,

Length of three sides of right angled triangle are (2x - 1) m, (4x) m, (4x + 1) m.

The largest side is hypotenuse = (4x + 1) m

By pythagoras theorem,

⇒ (2x - 1)2 + (4x)2 = (4x + 1)2

⇒ 4x2 - 4x + 1 + 16x2 = 16x2 + 8x + 1

⇒ 4x2 - 4x + 1 + 16x2 - 16x2 - 8x - 1 = 0

⇒ 4x2 - 12x = 0

⇒ 4x(x - 3) = 0

⇒ 4x = 0 or x - 3 = 0

⇒ x = 0 or x = 3

Since, x > 0.

∴ x = 3.

Hence, value of x = 3.

(ii) Calculating the sides of triangle,

Length of first side = 2x - 1 = 2(3) - 1

= 6 - 1

= 5 m

Length of second side = 4x

= 4(3)

= 12 m

Length of hypotenuse = 4x + 1

= 4(3) + 1

= 13 m

By formula,

Area of triangle = 12×\dfrac{1}{2} \times base × height

= 12\dfrac{1}{2} × 5 × 12

= 30 m2.

Hence, area of triangle = 30 m2.

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