A right circular cone is inscribed in a hemisphere.

In summary, a right circular cone is inscribed in a hemisphere with a constant rate increase of 18 in^2 per second in the combined surface area of the hemisphere and its base. The rate of change of the volume of the cone can be found by using the formula V= (1/3) &pi r3 and the calculated rate of change of the radius.
  • #1
pringless
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A right circular cone is inscribed in a hemisphere. The figure is expanding in such a way that the combinded surface area of the hemisphere and its base is increasing at a constant rate of 18 in^2 per second. At what rate is the volume of the cone changing when the radius of the common base is 4 in?
 
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  • #2
Are you sure this shouldn't be under "homework help"? :smile:

I assume that the cone is inscribed in the hemisphere so that its base is the circular base of the hemispher.

If I remember correctly, the surface area of a sphere is 4 &pi r2 so the surface area of a hemisphere is 2 &pi r2 and the "combinded surface area of the hemisphere and its base" is A= 3 &pi r2. Knowing that dA= 18 square inches per second, you should be able to find the rate of change of r from that.

The volume of a right circular cone is given by V= (1/3) &pi r2h (I confess I looked that up). In this case, the height of the cone, as well as the radius of its base, is the radius of the hemisphere so V= (1/3) &pi r3. Since you have already calculated dr/dt, you can use that to find dV/dt.

(Why are the "& codes" that Greg Barnhardt noted not working for me?)
 
  • #3
do they need to be (and are they) followed by semicolons?
 

1. What is a right circular cone?

A right circular cone is a three-dimensional geometric shape with a circular base and a curved surface that tapers to a point known as the apex or vertex. It is also sometimes referred to as a cone or right cone.

2. What is a hemisphere?

A hemisphere is a three-dimensional geometric shape with a flat base and a curved surface that forms half of a sphere. It is also sometimes referred to as a half-sphere.

3. How is a right circular cone inscribed in a hemisphere?

To inscribe a right circular cone in a hemisphere, the base of the cone must be exactly the same size as the flat base of the hemisphere, and the tip of the cone must touch the curved surface of the hemisphere at its highest point, known as the pole.

4. What are the properties of a right circular cone inscribed in a hemisphere?

Some properties of a right circular cone inscribed in a hemisphere include: the cone's base is a circle with the same radius as the hemisphere's base, the cone's height is equal to the hemisphere's radius, and the cone and hemisphere share a common axis of symmetry.

5. What are the applications of a right circular cone inscribed in a hemisphere?

A right circular cone inscribed in a hemisphere is commonly used in architecture and engineering for creating domes and other curved structures. It is also used in mathematics and geometry to demonstrate concepts such as inscribed shapes and volume calculations.

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