For this, the first thing to do is to assume that the function of temperature with respect to r is written in one of the following ways:
Way 1:

Way 2:

To find the instant variation we must find the derivative of the temperature with respect to the distance r.
We have then:
For function 1:


Rewriting

For function 2:


Rewriting

Answer:
The instantaneous variation of the temperature with respect to r is given by:
Assuming function 1:

Assuming Function 2:

I suppose you mean to have the entire numerator under the square root?

We can use a trigonometric substitution to start:

Then for
,
; for
,
. So the integral is equivalent to

We can write

so the integral becomes

Answer:
D
Step-by-step explanation:
Answer:
c
Step-by-step explanation: