Question

Choose the correct answer in each of the following questions:
1. The area of a triangle is 150 cm and its sides are in the ratio 3:4:5. What is its perimeter?
à. 10 cm b. 30 cm c. 45 cm d.60

Answer 1

Answer:

d

Step-by-step explanation:

we can proceed in two way

1. using heron formula for area of a triangle and finding the multiplier x.

2. using some analysis.

I am using the second one.

since sides are in the ratio of 3:4:5

let the sides be 3x, 4x and 5x

we can see that

(3x)^2 + (4x)^2 = (5x)^2

thus the triangle is a right angled triangle with 3x and 4x perpendicular to each other.

the area of triangle is 1/2 *base*height

1/2*3x*4x= 150

6*x^2= 150

x^2= 25

x= 5 ( taking positive value only)

thus sides are

3x=3*5=15 cm

4x=4*5=20 cm

5x=5*5=25 cm

hence, perimeter =15+20+25

= 60 cm (option d)