First thing to do with this problem is to plot the given data in MS excel. We can see in the graph that the minima (lowest point of the graph) is at (4,-2) and the maxima is at (2,3). The critical points are points which the direction changes from one side to another.
Answer:

Step-by-step explanation:
Answer:
3/2
Step-by-step explanation:
slope=rise/run=30/20=3/2
Answer:
In triangle SHD and triangle STD.
[Side]
Since, a line is said to be perpendicular to another line if the two lines intersect at a right angle.
⇒ 
[leg] [Given]
Reflexive property states that the value is equal to itself.
[Leg] [Reflexive property]
HL(Hypotenuse-leg) theorem states that any two right triangles that have a congruent hypotenuse and a corresponding congruent leg are the congruent triangles.
then, by HL theorem;
Proved!