# Find the value of c in a triangle, if the semi perimeter is 13cm and the values of a and b are 8cm and 7cm respectively.

Perimeter is the sum of all the sides of a triangle. The semi perimeter is half of the sum of all the sides of a triangle.

## Answer: If the semi perimeter is 13 cm and the values of a and b are 8 cm and 7cm respectively, then the value of c in a triangle is 11cm.

Let us solve this step by step.

**Explanation: **

Let S be the semi perimeter of the triangle

Perimeter (P) of the triangle is twice the semi perimeter (S)

Given: S = 13 cm

P = 2S

= 2 ✕ 13

=26 cm

We know that Perimeter of the triangle is sum of the three sides.

P = a + b + c

26 = 8 + 7 + c

26 = 15 + c

⇒ c = 26 - 15

⇒ c = 11 cm