EXPLANATION
We can apply the Obtuse Triangle Theorem to check if the the measures of the sides appropiately represents the measures of the triangle:
Perimeter = 40 cm = 4x + 2x + 2 + x + 3
Adding like terms:
40 = 7x + 5
Subtracting 5 to both sides:
40 - 5 = 7x
Adding like terms:
35 = 7x
Dividing both sides by 7:
35/7 = x
Simplifying:

Then, by the obtuse triangle theorem, the following relationship should be fulfilled.