All of the angles measure less than 90 degrees
No values of z make the equations true.
If you want to solve the equation
![R-C=P](https://tex.z-dn.net/?f=%20R-C%3DP%20)
for C, you can work like this: subtract P from both sides:
![R-C-P = 0](https://tex.z-dn.net/?f=%20R-C-P%20%3D%200%20)
Add C to both sides:
![R-P=C](https://tex.z-dn.net/?f=%20R-P%3DC%20)
We have a line tangent to the circle with center B at point C. We know that the angle formed between the tangent line at the point of intersection to the line extended from that point to the center of the circle is equal to 90°. In the problem, the 90° is for ∠BCA. We also know that the summation of all angles in a triangle is 180°. We have the solution below for the ∠BAC
180°=∠BAC + ∠BCA + ∠ABC
180°=∠BAC + 90° + 40°
∠BAC =50°
The answer is 50°.