Question

$\Delta ABC\cong \Delta LMN$. Perimeter of $\Delta LMN$ is $240$ cm. If the sum of two sides of $\Delta ABC$ is $130$ cm. What is the length of third side of $\Delta ABC$ ?

• A. $130$ cm
• B. $110$ cm
• C. $90$ cm
• D. $240$ cm

Answer 1

The correct option is B $110$ cm

$\Delta ABC\cong \Delta LMN$
Perimeter of $\Delta LMN$ is $240$ cm.
$\therefore$ perimeter of $\Delta ABC$ is $240$ cm (they are congruent).
Suppose, length of $AB+BC=130$ cm ....(given for any two sides)
$\therefore AB+BC+AC=240\Rightarrow AC=110$ cm
$\therefore$ length of third side of $\Delta ABC$ is $110$ cm.