The lengths of the sides of a triangle are 3,4,5. can the triangle be a right triangle?

We can use the Pythagorean theorem to test this.

a^2+b^2=c^2

If 3^2+4^2 is equal to 5^2 then it can be right angled.

3^2+4^2 = 25

5^2 = 25

Therefore it can be a right angled triangle.

Tip:

Learn a couple common Pythagorean triples to answer via inspection. These are 3 numbers that are always in a right angled triangle. If you know two of them, you’ll know the third.

3;4;5

6;8;10

5;12;13

9;12;15