Question

4) If the length of two sides of a triangle is 3cm and 7cm, and perimeter 15cm then what is the length of third side?​

Answer 1

Sides of triangle = 3 and 7 cm

Sum of these 2 sides = 10 cm

Perimeter = 15 cm

Third side = Perimeter - sum of 2 sides

= 15 - 10

= 5

Answer 2

Given:

the length of two sides of a triangle is 3cm and 7cm, and perimeter 15cm

To Find:

length of third side?

Solution:

perimeter of a triangle = sum of lengths of all three sides.!

so, now let the 3rd side be x

$: \implies \tt \: 15cm = 3 + 7 + xcm \\ \\ : \implies \tt \: 15cm = 10 + xcm \: \: \: \: \\ \\ : \implies \tt \: xcm = 15 - 10cm \: \: \: \: \\ \\ : \implies \tt x = 5cm \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \:$

$\blue{ \underline{ \boxed{ \pink{ \mathfrak{ \therefore \: the \: third \: side \: of \: the \: triangle = 5cm}}}}}$

hope this helps.!!