EasyCalculusca-058

Related Rates Circle Area

Problem

A circle has radius r and its radius is changing at rate drdt.

Since A = pi * r^2, the chain rule gives dA/dt = 2 * pi * r * (dr/dt). Return that rate, using pi = 3.141592653589793.

Hint

Differentiate A = pi r^2 with respect to time and use the chain rule.

case 1

in: [5,0.1]

expected: 3.141592653589793

case 2

in: [1,1]

expected: 6.283185307179586

case 3

in: [0,5]

expected: 0

case 4

in: [2.5,-0.4]

expected: -6.283185307179586

Starter codePython

def related_rates_area(r, drdt):
    # Your code here
    pass

4 test cases · run your code against them in the editor