Question

Will sides 4cm,5cm,12cm make a triangle ?

Answer 1

no

Explanation:

because a triangle should have at least two equal sides.

Answer 2

When three sides of a triangle are given,
find the sum of squares of smaller two sides, and square of largest side.

Note - if square of largest side is greater than the sum of squares of smaller two sides, the triangle is obtuse angled and if square of largest side is less than the sum of squares of smaller two sides, the triangle is acute angled.