The inclusion/exclusion principle states that

That is, the union has as many members as the sum of the number of members of the individual sets, minus the number of elements contained in both sets (to avoid double-counting).
Therefore,

will have the most elements when the sets

and

are disjoint, i.e.

, which would mean the most we can can in this case would be

(Note that

denotes the cardinality of the set

.)
3. We can see that
1+100=101
2+99=101
3+98=101
.................
and so on
From 1 to 100, there are 50 pairs that has the sum is 101
Z=101×50=5050
4. We can see that
1-2=-1
3-4=-1
5-6=-1
...........
and so on
There are 10 pairs that has sum is -1
Z= 10×(-1)=-10
Answer:
The second type of angle measures half the sum of the arcs it intercepts
How?
Its the first sentence in the lesson on the first section.
If you need anymore help lmk!