Maneuvering - seakeeping



Ok... undertood.
why the name is pie for symbol (π)?
to my understanding, π is representing half of the cake ( it is like apam balik, half of the cake).
So, the condition of :
1. when a cake (2π) is slice by 12 parts, then each person will get one slice with 30deg. Or in other words, 2π is divided to 12. (2π/12 = π/6). 
2. Next, if slice by 8, so each will get π/4 portion with 45deg. Where the value of π as initially known value is 3.142 ( short from the long list).
Ok... now, if we go for π, then for π/6, then 3.142/6= 0.524.  This value of 0.524 is in we called as radian.  Why we use radian? because it will represent the location in x, y direction from the 0 deg at first axis.

3. Here is the important remark. Let see on the π/3, if we look closely we will notice that the "trend" of the increasing of number of "slice".  It is π/3,  2π/3,  3π/3(which only denote as π),   4π/3 and lastly  5π/3.  
If we see other slice also the same, for slice 12.  The sequence is π/6, π/3, 2π/3,  5π/6,  7π/6,  4π/3,  5π/3 and lastly 11π/6.  The advantage of knowing this so we can calculate any degree by congaking or by only using our mind without using calculator machine.  
We know the coordinate for each slice (  e.g. for π/6, the coor is √3/2, 1/2....and followed by 
√2/2, √2/2   and lastly the third  is 1/2, √3/2 again-same as the first but only switch the x-y).  This is same for other side but only put minus sign for x-part.  And as we go below, it is minus minus, and last on is positive minus.

4. Radian means we convert the degree angle into 2π dimension(world). 2π is for 360deg.  And if we want portion of it, then divide by the slice that we want to.  

5. Problem: When we want the not common angle such as 35, 46, 55deg. So at that time we will use tangen-1 law to convert.  Let say for tanθ= π forms.  Then θ is 35 deg.  
tan 35deg = 0.7 (before π). If we to include π, then divide the 0.7 / π = 0.22.
So in the pie form, it should be 0.22π.

Very interesting of my finding own. =)
2019-2-27
14:32


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