<span>The answer should be this ∠ACB ≅ ∠DCB. I hope this helps</span>
Answer:
According to the passage, we have the next equation:

where "K" is a proportional constant
Leaving at the end with the next equation:

Integrating the equation, we have:

where "C" is a constant
Then, we have the 2 conditions for the problem:
1) t=0 → r=10
Replacing in the equation, we have C = 10
2) t=5 → r=8
Replacing in the equation, we have K = -0.4
Finally, the time which the snowball will be completely melted will be when r = 0. So replacing in the equation

t = 25 minutes
Because logarithms were a lot less time-consuming than other methods of finding roots. They were also more accurate in the sense that it was harder to make a mistake.
You need the Law of Sines for this. In our case we have the measure of angle B and side b, we have the measure of angle A and are looking for side a, or x. Setting up the Law using our info, we have

. We will solve for x by multiplying both sides by sin(42):

, first choice above.