Question

Find the perimeter of a triangle whose sides are in the ratio 3:4:5 and the longest side is 15 cm

Answer 1

Answer:perimeter =36 cm

Step-by-step explanation:since sides are in the ratio 3:4:5

we can assume sides to be 3x,4x,5x

and it is clear that 5x is the longest side which is equal to 15 cm

this shows that x=3 cm

making the sides 3x=3*3=9 cm

                              4x=4*3=12 cm

                              5x=5*3=15 cm

perimeter of the triangle= sum of all sides of a triangle=9+12+15=36 cm

Answer 2

Perimeter is the length of the given figure.

For Triangle, It can be defined as the sum of the three sides.

In the question,

Given data

1. The longest side is 15 cm.
2. The sides are in the ratio of 3 : 4 : 5

Solution :

Find which value of the ratio is greatest

Given ratio is 3 : 4 : 5

So, Here 5 is the greatest value.

Find the sum of terms in the ratio

3 + 4 + 5 = 12

Now Each side will the fraction of its value in the ratio by sum of ratios multiplied by some factor k

Longest side

⇒5/12 * k = 15

⇒5k = 180

⇒k = 36.

Now, Other two sides are

Side 1 : 3/12 * 36 = 3 * 3 = 9

Side 2 : 4/12 * 36 = 4 * 3 = 12

Side 3 : 5/12 * 36 = 5 * 3 = 15

Now,

Perimeter of triangle = Side 1 + Side 2 + Side 3

So, Perimeter = 9 + 12 + 15 = 36

Therefore, Perimeter of the given triangle is 36 cm.