What theorem states: the sum of the squares of the lengths of the sides of a right triangle is equal to the square of the length of the hypotenuse

The pythagorean theorem

The theorem is the Pythagorean theorem which states that a squared plus b squared equals c squared. 

If you open the bottle of perfume then nothing but the smell will come out of it and yes it is a type of gas smell because it’s say it in english so i can understand better and you

Yes, endothermic means it turns cold. and some chemical changes include change of tempature.