Question

The perimeter of a triangle is 18 cm and two of its sides measure 3.9 cm and 5.8 cm respectively. Find the third side.​

Answer 1

Step-by-step explanation:

perimeter = a + b +c sides

18 = 3.9 + 5.8 +c

18 = 9.7 + c

c = 18 - 9.7

c = 8.3

Answer 2

Given: The perimeter of a triangle is $18$cm and two of its sides measure$3.9$ cm and$5.8$ cm respectively.

We have to find the third side of the triangle.

As we know that the perimeter of the triangle is calculated by a formula:

$P=a+b+c$

Where,

a = Side  

b = Base  

c = Side

We are solving in the following way:

Let assume the third side of the triangle be'$x$'.

We have,

The perimeter of a triangle is $18$cm and two of its sides measure$3.9$ cm and$5.8$ cm respectively.

$P=a+b+c$

$=>18=3.9+5.8+x\\=>18=9.7+x\\=>x=18-9.7\\=>x=8.3$

Hence, the third side of the triangle will be$8.3cm.$