Volume of a cone using spherical coordinates with integration

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To find the volume of a cone with radius R and height H using spherical coordinates, the relevant equations are x = p cos(theta) sin(phi), y = p sin(theta) sin(phi), and z = p cos(phi). The angles theta range from 0 to 2π, while phi ranges from 0 to π/4, corresponding to the cone's geometry. The challenge lies in determining the value of p, which represents the distance from the origin to a point on the cone's surface. Correcting the equation for the cone is essential, and it is important to consider the coordinates at the circumference of the cone's widest part. Understanding these parameters will facilitate the integration needed to calculate the volume.
mahrap
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Find the volume of a cone with radius R and height H using spherical coordinates.


so x^2 + y^2 = z^2
x = p cos theta sin phi
y= p sin theta sin phi
z= p cos phi

I found theta to be between 0 and 2 pie
and phi to be between 0 and pie / 4.
i don't know how to find p though. how would i do this.
 
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mahrap said:
so x^2 + y^2 = z^2
That does not fit the given dimensions.
x = p cos theta sin phi
y= p sin theta sin phi
z= p cos phi

I found theta to be between 0 and 2 pie
and phi to be between 0 and pie / 4.
i don't know how to find p though. how would i do this.
After correcting the equation for the cone, consider the coordinates of a point at the circumference at the widest part of the cone.
 
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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