The Law of Cosines features the 3 side lengths of a triangle, plus the measure of the angle opposite one of those sides.
We want angle x, which is opposite the side of length 39.
Then: a^2 = b^2 - 2ab cos C becomes 39^2 = 36^2 + 59^2 - 2(36)(59)cos x
or 1521 = 3481 + 1296 - 2(36)(59) cos x
Subtract (3481+1296) from both sides: 1521 - 4777 = -4248cos x
-3256 = -4248cos x
-3256
Then: cosx = --------------- = 0.766
-4248
Solving for x: x = arccos -0.766 = 0.698 radian, or 40 degrees (answer)
The 3.1 °F/min rate of change of the temperature and 15 minutes change duration gives the change in temperature as 46.5 °F
<h3>How can the change in temperature be found from the rate of change?</h3>
The rate at which the temperature changed = 3.1 °F/min
The duration of the change in temperature = 15 minutes
The relationship between the change in temperature, the rate of change in temperature and the time can be presented as follows;

Where;
∆T = The required change in temperature
∆t = The duration of the change = 15 minutes
Which gives;
∆T = 3.1°F/min × 15 minutes = 46.5 °F
- The change in temperature, ∆T = 46.5 °F
Learn more about the rate of change of a variable here:
brainly.com/question/10208814
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This is because two angles are zero and top is a straight line, and a line is 180 degrees!
hopes this helps :)