Question

Can i use the pythagorythm therom on all triangles

Answer 1

No, you can only use the Pythagorean theorem on right triangles. 

Answer 2

Pythagoreans' theorem only applies to right angle triangles.

To find unknowns of an irregular triangle use

a² = b² + c² -2bc cos A
( for length and angle )

and

½ ab sin C ( for area )