Double angle (or half angle, depending how you look at it) identities:
So we have
Note that when taking the square root, we should take into account that that could yield two possible solutions, but we know 
and 
, so it's also the case that 
.
Also, the reason we have equality in the last step can be explained like so:
(not unlike the process used to complete the square)
1:3 because 13/39 is basically 1/3 when simplified
Answer:
28, 29, and 30
Step-by-step explanation:
There's probably better ways but you can estimate by knowing 30*3=90 so it should be somewhere pretty close to 30. Guess and check with basic calculations to get 28, 29, and 30.
To arrange numbers from least to greatest:
First write them down in decimal form. Now it will be easy to determine which value is greater than the other.
Arrange the decimal numbers from least to greatest.
Finally revert the decimal values to their fraction form having arranged them from one with least value to one with greatest value.
