Answer:

Step-by-step explanation:
Distance between two points:
Suppose that we have two points,
and
. The distance between them is given by:

Equation of a circle:
The equation of a circle with center
and radius r has the following format:

Center at the origin;
This means that 
So



Passes through (4, 6)
The radius is the distance from this point to the center. So




So

Then


This question is the application of differential eqns in order to derive a model for the temperature dependence with time. Actually, a general equation has already been derived for this type of cases. This equation is known as the Newton's Law of Cooling. The equation is
(T - Ts) / (To -Ts) = e^(-kt)
where T is the the temperature at any time t
Ts is the surrounding temperature
To is the initial temperature
k is the constant
t is the time
several assumptions have been made to arrive at this form, i suggest you trace the derivation of the general formula.
First we need to look for k using the initial conditions that is @t = 1.5 min, T = 50 F
substituting we get a k = 0.2703
therefore @ t = 1 min, T = 55.79 F
@ T = 15 F the time required is 9.193 min.
A=42
C=90
B=48
We can reason that C will be equal to 90 since it is the right angle. So to find B we have to subtract 90 from 180 to get 90 then subtract 42 to get 48
B=48 degrees