Here is an example... ( look at the attachment bellow ) :
Answer:
The radius is: 
Step-by-step explanation:
The equation of a circle in center-radius form is:

Where the center is at the point (h, k) and the radius is "r".
So, given the equation of the circle:

You can identify that:

Then, solving for "r", you get that the radius of this circle is:

Answer: 10y
Step-by-step explanation: All variables equal one unless assigned a specific answer. So It is basically 9y+1
9y+1=10y
Final Answer: 10y
Hope this helps! :D
Answer:
m∠P = 107º
Step-by-step explanation:
Since two sides are parallel this is a trapezoid
In a trapezoid, the angles on the same leg (called adjacent angles) are supplementary, meaning they add up to 180 degrees.
(7x + 31) + (21x - 19) = 180
combine like terms
28x + 12 = 180
Subtract 12 from both sides
28x = 168
Divide both sidees by 28
x = 6
m∠P = 21x - 19
m∠P = 21(6) - 19
m∠P = 107º