How Do You Calculate the Volume of a Cone Using Integration?

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To calculate the volume of a right circular cone using integration, the volume can be expressed as V = ∫ A(y) dy, where A(y) is the area of horizontal slices. The area of each slice depends on the radius, which varies with height, requiring a relationship between the radius and height of the cone. A vertical cross-section sketch reveals that the cone forms a triangle, aiding in establishing this relationship. The discussion emphasizes the importance of correctly setting up the integral with respect to height rather than using an incorrect variable. Understanding these concepts is crucial for successfully finding the volume of the cone through integration.
the_storm
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Homework Statement



Using integration, Find the Volume of a right circular cone with height h and base radius r

The Attempt at a Solution


since the volume is
V(x) = \int A(x) d(x)
so I divided the cone into horizontal circles with radius r and r = \sqrt{s^{2} + y^{2}} where is the hypotenuse and y is the height of the cone.
then I integrate with respect to y, but I got nothing so is there any help to find the volume of the cone ?
 
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the_storm said:

Homework Statement



Using integration, Find the Volume of a right circular cone with height h and base radius r

The Attempt at a Solution


since the volume is
V(x) = \int A(x) d(x)
Your integral won't look like this since you are using horizontal slices, each of width dy. The area of each slice is a function of y, not x.
the_storm said:
so I divided the cone into horizontal circles with radius r and r = \sqrt{s^{2} + y^{2}} where is the hypotenuse and y is the height of the cone.
then I integrate with respect to y, but I got nothing so is there any help to find the volume of the cone ?
Draw a vertical cross-section sketch of the cone, with the base on the horizontal axis and the vertex of the cone at (0, h). The cross section will be a triangle.

What is the equation of the right side of the triangle? You need to find a relationship between the radius of a slice and the height of the slice.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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