Without experience that would help you recognize it right away, I think
you would just need to try numbers until you find it.
Pick a number, multiply it by itself with pencil and paper, and see if it works.
(2)² = 4 too small
(3)² = 9 too small, and not growing fast enough; this could take all day
(10)² = 100 still too small
(15)² = 225 oops, too big; go back down
(12)² = 144 too small
(14)² = 196 too big
(13)² = 169 just right; hope the bears don't come back too soon
1) The definition of a scalene triangle is that ALL sides are different.
Now, to prove a triangle is scalene, we need to show that all three sides output different values. Therefore, selections with only two sides certainly are insufficient. If we look at the last two choices, you can easily spot that the second to the last is correct answer by comparing the definition of a scalene triangle.
2) You will need to perform something similar to the previous questions, which is, find the distance between the three points, and see if they are all different => scalene; all the same => equilateral; or two of them are the same => isosceles.
The distance formula between two points (a, b) and (c,d) is given as:

Just for you to check your work, the distances between three points are:
sqrt(34), sqrt(17), sqrt(37), which results a scalene triangle.
Here ya go
53-bbb
54-c
55-ddd
56-eee
57-aaaga
if you have questions on the way I wrote it please ask
16 is your answer have a great day