What are two ratio equivalent to 5/9

Which statement is true 1.the pythagorean theorem can be used to find the missing side of any triangle 2.the pythagorean theorem can be used to find the missing side of any polygon 3. the pythagorean theorem can be used to find the missing side of any right triangle 4.the pythagorean theorem can be used to find the missing side of any isosceles triangle

In two or more complete sentences describe how to determine the appropriate model for the set of data, (1,1), (3,2), (6,3), (11,4).

Atriangle has a side lengths of 18cm, 80 cm and 81cm. classify it as acute obtuse or right?