Is it possible to draw a tringle with 90 Angle and one leg that is 8 centimeters long and one leg that is 6 centimeters long? is there more than one such tringle that exists with these conditions?

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 ...