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If the difference between the two sides of a right-angled triangle is 2 cm and the area of the triangle is 24 cm2; find the perimeter of the triangle.

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If the difference between the two sides of a right-angled triangle is 2 cm and the area of the triangle is 24 cm2; find the perimeter of the triangle. Chapterwise Revision (Stage 1), Concise Mathematics Solutions ICSE Class 9.

ABC is a right angled triangle with a right angle at B.

The difference between the two perpendicular sides is 2 cm.

The area of the triangle is 24 cm2.

Let the lengths of BC and AB be a and b, respectively.

From the given condition:

a - b = 2

∴ b = a - 2

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

12\dfrac{1}{2} x BC x AB = 24

12\dfrac{1}{2} x a x (a - 2) = 24

⇒ a x (a - 2) = 24 x 2

⇒ a2 - 2a = 48

⇒ a2 - 2a - 48 = 0

⇒ a2 - 8a + 6a - 48 = 0

⇒ a(a - 8) + 6(a - 8) = 0

⇒ (a - 8)(a + 6) = 0

⇒ a = 8 or -6

Since length cannot be negative, a = 8 cm.

Now, substituting a = 8 in b = a - 2:

b = 8 - 2 = 6 cm

By using Pythagoras theorem,

Hypotenuse2 = Base2 + Height2

⇒ AC2 = BC2 + AB2

= 82 + 62

= 64 + 36

= 100

⇒ AC = 100\sqrt{100}

= 10 cm

Perimeter of the triangle = Sum of all sides of the triangle

= AC + BC + AB

= 10 + 8 + 6 cm

= 24 cm

Hence, the perimeter of the triangle is 24 cm.

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