Math Portfolio

Math Portfolio

HL- Type 1

INVESTIGATINGRATIOS OF AREAS AND VOLUMES

The purpose of this portfolio is to investigate the ratios of areas and volumes when a function y= xn   is graphed between two arbitrary parameters x=a and x=b such that a‹b.

Task 1

The general formula to find area A is [pic]

The general formula to find area B is [pic]

Therefore, the ratio of Area A to Area B is-

= [pic] ÷ [pic]

= [pic] × [pic]

= n : 1

n:1 is the general conjecture formed.

The given function is in the form of y=xn. The function is y=x2. As mentioned above the parameters are between x=a and x=b. Here a=0 and b=1.

The graph of the function-

[pic]

y=xn where n=2.

The Area of the shaded region or area B was found to be 0.3333333333 units2.
Area A = 1- Area B
            = 1- 0.33333333
            = 0.6666666666 units2

Mathematically the area can also be found by the following-
Area A can be found by the formula-   [pic]
Area B can be found by the formula-   [pic]

Total Area = 1 unit2

Area B = [pic]

              = [pic]

Area A = [pic]

              = [pic]

Ratio of area A : area B
[pic]   : [pic]
= 2 : 1(satisfies the conjecture n:1)

Now I will investigate the ratios of area A and B with other natural numbers.

This means that the function will stay y=xn but here only n will change. The parameters will stay the same a=0 and b=1.

The ratios when n =3
The graph of y=x3
[pic]
Y=xn where n=3.

The Area of the shaded region or area B was found to be 0.25 units2.
Area A = 1- Area B
            = 1- 0.25
            = 0.75 units2

Mathematically the area can also be found by the following-
Total area = 1unit2

Area B = [pic]

              = [pic]

Area A = [pic]

              = [pic]

Ratio of area A : area B
[pic]   : [pic]
= 3 : 1(satisfies the conjecture n:1)

Now I will investigate the ratio of the areas for n being a rational number.
The ratio when n= [pic]
Y = x0.5

[pic]... [continues]

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