Answer:
The value of variable r in the equation
is 
Step-by-step explanation:
We need to find the value of variable r in the equation 
Step 1: Write the equation

Step 2: Subtract 4 on both sides

Step 3: Divide both sides by 4

So, The value of variable r in the equation
is 
Answer:
<h2>h = 4 cm</h2><h2 />
Step-by-step explanation:
V = π r² h
where r = 3 cm
V = 36π cm³
solve for h
plugin values into the formula:
36π = π 3² h
h = <u> 36π </u>
π 3²
h = 4 cm
The vertex of the graph is (2,-4). It is a minimum as it is the lowest point on the parabola facing upwards. This would be option C.