Question

The lengths of sides of a triangle are in the ratio 3 : 4 : 5 and its perimeter is 120 cm, find its area.

300 sq cm

400 sq cm

500 sq cm

600 sq cm

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Answer 1

Answer:

600 cm²

Step-by-step explanation:

So we know that the perimeter is 120 cm and the lengths of the sides are in the ratio 3:4:5. So that means that each side is 3x, 4x and 5x (taking one unit as x). So,

3x + 4x + 5x = 120cm

12x = 120 cm

x = 10cm

So each side is:

3x = 3 (10) = 30cm

4x = 4 (10) = 40cm

5x = 5 (10) = 50cm

Using pythagoras theorem, we can say that this triangle is a right angled triangle.

Using the 40 cm side as base, area will be:

1/2 x 40cm x 30cm (Since 30 cm will be the height)

=20cm x 30cm

600 cm²

So your answer is 600cm²