Question

two sides of a triangle are 18cm and 13 cm.the perimeter of the triangle is 42cm.find its third side.

Answer 1

Given= two sides 18 cm and 13 cm ..

perimeter = 43cm.

now ,,, ( let the another side be x

Perimeter of the triangle= sum of all the sides ..
42 = 18+13+ x
42= 31+x
x= 42-31
x= 11 cm ..

theirfore,, 11 cm is the required side .

Answer 2

perimeter of triangle=42
1st angle=18
2nd angle=13
3rd angle=x,
18+13+x=42
x=42-31=11