Yes it is The hypotenuse is 10 cms long.
Because its a right angled triangle ( 90 angle) the hypotenuse will be 10 cms long - it will obey the Pythagoras theorem:-
10^2 = 8^2 + 6^2
There is only one right angled triangle with these measurements but there are many of them which have sides in same ratio
for example
3, 4 and 5
9,12 and 15
12, 16 and 20 and so on..
Answer and Step-by-step explanation

2, -4, 6, -8, 10, -12, 14, -16
These are the next three numbers in the pattern :-12, 14, -16
Examples would be 2+6 = 8 with two of the integer that are different
The diameter is 18.8 feet
I believe the circumference is 59.0 feet
See the attached figure. The original triangle is shown in red (triangle ABC). The line of reflection is the blue dashed line. This is the equation y = x. Reflecting triangle ABC over the line y = x results in the purple triangle A'B'C'.
Note how the x and y values swap places.
We have...
point A = (5,1) turn into point A' = (1,5)
point B = (8,1) turn into point B' = (1,8)
point C = (8,6) turn into point B' = (6,8)
The swap occurs because the rule (x,y) --> (y,x) tells this to happen.
The purple triangle is the final answer.