Question

If perimeter of a triangle is 39 cm, and two of side are 15 am and 11 cm , find the third side.
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Answer 1

Answer:

13

perimeter of triangle = sum of all sides

39=15+11+third side

third side =39-26

third side = 13

Answer 2

Answer:

The third side of the triangle is 13 cm.

Step-by-step explanation:

Let the third side be x cm

Here (Given),

Length of two sides = 15 cm and 11 cm,respectively.

Perimeter of the triangle = 39 cm

We know,

Perimeter of a triangle = Sum of its three sides

∴, According to the question :

$39 = 15 + 11 + x$

$= > 39 = 26 + x$

$= > 26 + x = 39$

$= > x = 39 - 26$

$∴x = 13$

Therefore, the third side is 13 cm.

For Verification :

We know,

Perimeter of a triangle = Sum of its three sides

By substituting the values , we get :

L. H. S. । R. H. S

Perimeter I Sum of all three sides

39 cm l 15 cm + 11 cm + 13 cm

39 cm l 39 cm

Thus, LHS = RHS

Hence, the answer is correct.