Question

Two sides of a triangle are $13cm$ and $14cm$ and its semi-perimeter is $18cm$. Then third side of the triangle is

• A. $12cm$
• B. $11cm$
• C. $10cm$
• D. $9cm$

Answer 1

Answer: (D)

$9cm$

Let $a=13cm$, $b=14cm$, and third side $=c$ $cm$

Semiperimeter is half of perimeter and is given by,

$s=\frac{a+b+c}{2}$

$\Rightarrow 18=\frac{13+14+c}{2}$

$\Rightarrow c=36-27$

$\Rightarrow c=9cm$

$\therefore$ Third side of the triangle is $9cm$.