Answer
(-2,8)
Step-by-step explanation:
Answer:



Step-by-step explanation:
Given




Required
The dimension that minimizes the cost
The volume is:

This gives:

Substitute 


Make H the subject


The surface area is:
Area = Area of Bottom + Area of Sides
So, we have:

The cost is:



Substitute:
and 



To minimize the cost, we differentiate

Then set to 0


Rewrite as:

Divide both sides by W

Rewrite as:

Solve for 


Take cube roots

Recall that:







Hence, the dimension that minimizes the cost is:



Answer:
22.5°
Step-by-step explanation:
First we need to figure out the size of the interior angles on the inside.
The formula of figuring out the total degrees of all the interior angles of any shape is (n-2)×180°.
N is the number of sides.
If we substitute our number of sides (8) we get this:
(8-2)×180°
6×180° = 1080°
Then we divide 1080 by 8 since this is a regular octagon (all angles are equal in a regular shape).
1080° ÷ 8 = 135°
Focusing on the triangle now, we now know that the angle on the tip of the triangle is 135° as it has not been split by the line.
Using the rule of angles in a triangle add up to 180°. We do this sum:
180° - 135° = 45°
There are 2 angles left in the triangle so we do:
45° ÷ 2 = 22.5°
Therefore the angle of x is 22.5°.