Answer:
The candle has a radius of 8 centimeters and 16 centimeters and uses an amount of approximately 1206.372 square centimeters.
Step-by-step explanation:
The volume (), in cubic centimeters, and surface area (
), in square centimeters, formulas for the candle are described below:
(1)
(2)
Where:
- Radius, in centimeters.
- Height, in centimeters.
By (1) we have an expression of the height in terms of the volume and the radius of the candle:
By substitution in (2) we get the following formula:
Then, we derive the formulas for the First and Second Derivative Tests:
First Derivative Test
There is just one result, since volume is a positive variable.
Second Derivative Test
If :
(which means that the critical value leads to a minimum)
If we know that , then the dimensions for the minimum amount of plastic are:
And the amount of plastic needed to cover the outside of the candle for packaging is:
The candle has a radius of 8 centimeters and 16 centimeters and uses an amount of approximately 1206.372 square centimeters.