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The base of a right angled triangle is 12 cm and its hypotenuse is 13 cm long. Find its area and the perimeter.

Mensuration

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Answer

It is given that,

ABC is a right angled triangle.

The base of a right angled triangle is 12 cm and its hypotenuse is 13 cm long. Find its area and the perimeter. Mensuration, ML Aggarwal Understanding Mathematics Solutions ICSE Class 9.

From figure,

BC = 12 cm and AC = 13 cm

Using the Pythagoras theorem,

AC2 = AB2 + BC2

Substituting the values we get,

⇒ 132 = AB2 + 122

⇒ AB2 = 132 – 122

⇒ AB2 = 169 – 144 = 25

⇒ AB = 25\sqrt{25} = 5 cm.

We know that,

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

Substituting the values we get,

A = 12×12×5\dfrac{1}{2} \times 12 \times 5 = 30 cm2.

Perimeter of triangle ABC (P) = AB + BC + CA

Substituting the values we get,

= 5 + 12 + 13

= 30 cm.

Hence, area of triangle = 30 cm2 and perimeter = 30 cm.

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