Question

1. Check if the triangle is right-angled.2. Check if the base is equal to the side.

Answer 1

We will check if a triangle with sides

$a=31.8\text{ cm},\text{ }b=6cm,\text{ }and\text{ c=}7.8cm$

Is a right angle.

Solution:

Note that in any triangle we have to satisfy the triangle inequality, that inequality says that:

For any triangle, the sum of the lengths of any two sides must be greater than or equal to the length of the remaining side.

With the measures provided for the sides in this question, we confirm that:

$7.8+6=13.8<31.8$

Then, the measures does not satisfy the triangle inequality, in consequence there are not exist triangle with such measures, and follows that neither a right triangle.