Hello, lysserloo!

We can solve this without using Trig.

A coffee filter in the shape of a right circular cone with a base radius of 6cm and depth 10cm

contains water, which drips out through a hole at the bottom at a constant rate of 2 cm³/sec.

How fast is the water level falling when the depth is 8 cm? Code:

: - 6 - : - 6 - :
- *-------+-------*
: \ | /
: \ | r /
: \- - + - -/
10 \ | /
: \ h| /
: \ | /
: \|/
- *

The volume of the water is: . .[1]

From the similar right triangles: .

Substitute into [1]: .

Differentiate with respect to time: . .[2]

We are given: .

Substitute into [2]: .

Therefore: . cm/sec.