Answer:
x = 2root(22)
see image.
Step-by-step explanation:
The triangle shown is one big triangle cut into two more smaller triangles: one medium-sized and one smaller.
ALL THREE TRIANGLES ARE SIMILAR BY AA.
Set the two smaller triangles up so you can see the corresponding sides. x is the short leg in one triangle and it is the long leg in the smallest triangle. Set up a proportion.
22/x = x/4
crossmultiply
x^2 = 22•4
x^2 = 88
square root both sides.
x = sqroot(88)
x = 2sqroot(22)
see image.
The two parabolas intersect for
and so the base of each solid is the set
The side length of each cross section that coincides with B is equal to the vertical distance between the two parabolas, . But since -2 ≤ x ≤ 2, this reduces to
.
a. Square cross sections will contribute a volume of
where ∆x is the thickness of the section. Then the volume would be
where we take advantage of symmetry in the first line.
b. For a semicircle, the side length we found earlier corresponds to diameter. Each semicircular cross section will contribute a volume of
We end up with the same integral as before except for the leading constant:
Using the result of part (a), the volume is
c. An equilateral triangle with side length s has area √3/4 s², hence the volume of a given section is
and using the result of part (a) again, the volume is
