Hi!
A function is when you can look at any number on the graph, and it only has one value in the line. For example, look at 2 on the y-axis. It only has one point on the line, but -2 on the y-axis has two points on the line. I hope that makes sense.
Therefore the answer is B. No, because some of the y-values are paired with 2 x-values.
Hope this helps! :)
-Peredhel
Area of base is Circumference x
or A = 25 x 
A = 78.53981
Volume = Area of Base x Height or V = 78.53981 x 8
V = 628.32 Units
The volume of the cylinder is 628.32 units
What Do you need help with if you added a picture we cant see it
You have to prove that 2 angles are conguent to the other triangles angles; example: ∠A≅∠C by the additon POC (2 of those) and then one side; example: AB≅BA by the reflexive POE (1 of those)
I cant see the triangles but thats how you do them, also im learning this right now too, look up the triangle congruence things like ASA ≅ SSS≅ HL≅ exc. a chart will explain how to prove them using that: