8,663,900,000
.......................
You can try to show this by induction:
• According to the given closed form, we have
, which agrees with the initial value <em>S</em>₁ = 1.
• Assume the closed form is correct for all <em>n</em> up to <em>n</em> = <em>k</em>. In particular, we assume

and

We want to then use this assumption to show the closed form is correct for <em>n</em> = <em>k</em> + 1, or

From the given recurrence, we know

so that






which is what we needed. QED
You would need to know the length of two sides either a2, b2, c2. you would also need to know what sides you are solving for, either one of the legs or hypotenuse. hope this helps, if you know how to solve a Pythagorean theorem problem this should be easy to answer
This one isn’t really that hard. the answer is 24.
They are always on a coplanar