Help? ill mark brainlist if available :)

Select the lengths in centimeters that would form a right triangle

Sanya noticed that the temperature was falling at a steady rate of 1.4 degrees every hour from the time that she first checked her outdoor thermometer. by 6 a.m., the temperature had fallen 21 degrees. which expression can you use to find how many hours earlier she had first checked the thermometer?

Identify reflection rule on a coordinate plane that verifies that triangle a(-1,7), b(6,5), c(-2,2) and a’(-1,-7), b(6,-5), c’(-2,2) triangle are congruent when reflected over the x-axis