Answer:
We can prove the similarity of two circles by mapping one circle onto the other (i.e. making a circle look exactly like the other one) by a translation and a scale factor.
Let's map circle Y onto circle X for example. We need to make sure we have the same radii for both circles, so let's expand circle Y by a scale factor of 2. Then shift circle Y 6 units up and 6 units to the left to move the center point of circle Y over to that of circle X.
Now, since we could map circle Y onto circle X using transformations (scaling and translation), we know that the two circles are similar.
Answer: D. Triangle
Step-by-step explanation: Because if you cut it in half it gives you a triangle
we can use pythagorean identieis
remember that 
also remember that 
and 
so if we take and divide both sides by 
we get
subtracting 
from both sides
now subsitute into original problem
the answer is -1
Hi.
16 + x + 21
Hope I was right in understanding your question.
