There is a formula that relates the number of sides of a regular polygon to its interior angle. It is the following:
\(\frac{180(n-2)}{n}\)
This formula will tell you the interior angle measure, if given the number of sides. However, we have the interior angle measure! So, just solve for n, the number of sides.
\(\frac{180(n-2)}{n}=170\) | Multiply by n on both sides to get rid of the pesky fraction. |
\(180(n-2)=170n\) | We can divide both sides by 10 to keep the numbers relatively small. |
\(18(n-2)=17n\) | Distribute inside of the paretheses. |
\(18n-36=17n\) | Subtract 18n from both sides. |
\(-36=-n\) | Divide by -1 on both sides to isolate n. |
\(n=36\) | |
Therefore, this polygon has 36 sides.
I am ??!!??!?!?!?!?!!? Well, thank you!
I wish I could explain how I got that answer.
I will give my best attempt, I guess.
Column 1 | Column 2 | Column 3 | Column 4 | Column 5 | |
Row 1 | L | L | |||
Row 2 | L | O | O | L | |
Row 3 | L | O | O | O | L |
Row 4 | C | C | C | C | C |
This is just one side of the table. I have color coded the O's such that if you land on an O as your second-to-last letter, then you will have a certain number of possibilities.
A red O means there are 3 possibilities.
A Blue O means there are 2 possibilities.
Hopefully, you can see why this is the case.
Let's start with the easiest: The "C" in the corner. Before I start, I will use my own style of Cartesian coordinates where it represents the intersection of a column and a row. For example, \((C1,R1)\) is (Column 1, Row 1), for short. In this case, this letter happens to be L.
There is only one case to consider now for the corner "C." It is the following:
1) \((C5,R4)\Rightarrow(C4,R3)\Rightarrow(C4,R2)\)
Look at that! I have landed on a red O, which signifies 3 possibilities. This means that the corner "C" has 3 possibilities. There are 4 instances of the corner "C," so 4*3=12
Time to consider the next case: The "C" adjacent to the corner "C"
Now, let's consider how many cases there are for the sequence \((C4,R4)\Rightarrow(C3,R3)\). Well, the number of possibilities is equal to the sum of the number of possibilities its neighbors are immediately adjacent to.
\((C3,R3)\) is adjacent to 2 red and 2 blue O's. Because there are 3 possibilities for a red one and 2 possibilities for a blue one, the number of possibilities is \(3+3+2+2=10\). However, this is only one sequence. Let's consider the next sequence of \((C4,R4)\Rightarrow(C4,R3)\Rightarrow(C4,R2)\). Oh look! This is a red "O," which has 3 possibilities, so let's add the number of possibilities together.
\(10+3=13\)
There are 4 of these in the diagram, so \(13*4=52\)
Now, let's consider the center "C." Well, we can use the same logic as before to know that \((C3,R4)\Rightarrow(C3,R3)\) has 10 possibilities. We know that there are 2 avenues to red O's, which equals 6 additional paths.
In total, that equates to \(10+6=16\) ways. There are two instances of there, so \(2*16=32\)
The last step is to add the numbers together. \(12+52+32=96\) ways.