Answer:

Step-by-step explanation:
This answer is easily found using the Pythagorean Theorem:

where A and B are the legs, and C is the hypotenuse of the triangle.

There are 3 nickels because if you use the ratio 6 to 1 you multiply 6 by 3 to get 18 pennies and you do the same with the one and that’s how I got 3 nickels.
The one that passes through the origin. That one in the lower left part.
49 only has one square root, which is 7. There is no other number that you can multiply by itself to get 49