Answer:
it would be 11475 hope this helps :)
Let's start from what we know.

Note that:

(sign of last term will be + when n is even and - when n is odd).
Sum is finite so we can split it into two sums, first

with only positive trems (squares of even numbers) and second

with negative (squares of odd numbers). So:

And now the proof.
1) n is even.
In this case, both

and

have

terms. For example if n=8 then:

Generally, there will be:

Now, calculate our sum:



So in this case we prove, that:

2) n is odd.
Here,

has more terms than

. For example if n=7 then:

So there is

terms in

,

terms in

and:

Now, we can calculate our sum:




We consider all possible n so we prove that:
The answer is 16
Refer image for working :-
Drop comments if any doubt arises.
Answer:
120 degrees
Explanation:
Opposite angles (angles that are on opposite sides of an intersection) are equal to each other. Because angle 2 and 120 degrees are opposite angles, angle 2 is equal to 120 degrees.
I hope this helped if it did, a brainliest would be much appreciated:)
Answer:
C. a triangle
Step-by-step explanation:
hope this helps c: