Answer:

Step-by-step explanation:
Use the circle equation, 
Plug in the center and radius:

Simplify:

So, the equation is 
If is an acute triangle, all the angles should be acute angles.
180-38=142°
142-69=73°
So your answer is 69°, lovely~
<u><em>Answer:</em></u>
c = 4
<u><em>Explanation:</em></u>
The number of solutions for any equation is equal to the degree of the equation.
The given equation is a second degree equation which means that it has two solutions.
The only possible way for it to have one unique real solution is that the two <u>solutions are equal</u>
<u>This means that:</u>
x - 4 = x - c
<u>Now, we solve for c:</u>
x - 4 - x = x - c - x
-4 = -c
c = 4
Hope this helps :)