15(100) + 5d+ 20(50) + 7d=d
1500+ 1000+ 12d=d
2500+12d=d
This likely has a pattern. Lets see if we can find it.
The sum of a triangle is 180
The sum of a 4 sided figure is 360
The sum of a 5 sided figure is 3*180 = 540
The sum of a 6 sided figure is 4*180 = 720
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The pattern looks like it it (( n-2 )*180) for any polygon where n is the number of sides of the polygon.
You can convince yourself (but this is not a formal proof) by starting with a 6 sided figure. Pick one point on the figure where 2 sides meet. Draw diagonals to all the points not connected to the point you've chosen. You should be able to get 4 such diagonals. You have created 4 triangles.
4*180 = 720 just what your estimate said.d
8 sides will give 6*180 = 1080 degrees and if you keep going on the above table you will see 1080 come up for 8. I'd post a diagram but I don't know how to upload it.
This procedure is extremely important. There is a new math around where these kinds of problems are solved by reducing them to much simpler questions, and getting an answer for them. The pattern is what you are looking for.
Now you can do the rest of the questions.
Pentagon: (5 - 2) * 180 =
Octagon: (8 - 2) * 180 =
dodecagon (12 - 2)*180=
40 sides 38*180 =
100 sides 98 * 180 =
Answer:
This proof can be done by contradiction.
Let us assume that 2 - √2 is rational number.
So, by the definition of rational number, we can write it as
where a & b are any integer.
⇒ 
Since, a and b are integers 
is also rational.
and therefore √2 is rational number.
This contradicts the fact that √2 is irrational number.
Hence our assumption that 2 - √2 is rational number is false.
Therefore, 2 - √2 is irrational number.
Answer:
Step-by-step explanation:
