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Mathematical error in CAD?

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KingsDaughter View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote KingsDaughter Quote  Post ReplyReply Direct Link To This Post Topic: Mathematical error in CAD?
    Posted: 18.Apr.2018 at 19:03
I have a triangle shaped area of property. In labeling the lines, CAD gives an incorrect answer for the hypotenuse of the triangle. It should be 73.85 and CAD shows it as 73.997. What's up with that and is there a setting I need to change to get the correct length?


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Kent Cooper View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kent Cooper Quote  Post ReplyReply Direct Link To This Post Posted: 18.Apr.2018 at 19:36
That would be about right if it were a right triangle, but the other two edges are not perpendicular to each other.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KingsDaughter Quote  Post ReplyReply Direct Link To This Post Posted: 18.Apr.2018 at 19:48
Good catch, Kent Cooper! I changed the decimal setting and discovered the angle is 90.314. Thank you! Sometimes you just need more eyes on the problem to see it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kent Cooper Quote  Post ReplyReply Direct Link To This Post Posted: 18.Apr.2018 at 20:42
You can see it without having to draw an angular Dimension.  In that kind of situation, depending on the specific directions, the degrees-minutes-seconds parts of the metes and bounds for two lines would have to have either their sum or their difference equal to 90 degrees for them to be perpendicular.  Just looking at the sum of the degrees and minutes parts for that triangle's legs, you get only to 89 degrees 40 minutes.  The seconds adds about another arc-minute, but the total is clearly not going to be 90 degrees.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kent Cooper Quote  Post ReplyReply Direct Link To This Post Posted: 19.Apr.2018 at 18:36
Originally posted by Kent Cooper Kent Cooper wrote:

.... the degrees-minutes-seconds parts of the metes and bounds for two lines would have to have either their sum or their difference equal to 90 degrees for them to be perpendicular.  ....
 
[I just realized I was wrong about that -- it's only the sum.  Surveyor's Units D-M-S values never reach or exceed 90 degrees.]
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mypushpi Quote  Post ReplyReply Direct Link To This Post Posted: 18.Oct.2018 at 11:01
The values of lengths and angles which displaying in drawing are not right accurate. there are some digits remaining, but not displaying in our parameter. so it is very close to, but not equal to value. Answers depend on accuracy.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kent Cooper Quote  Post ReplyReply Direct Link To This Post Posted: 18.Oct.2018 at 19:09
Originally posted by mypushpi mypushpi wrote:

The values of lengths and angles which displaying in drawing are not right accurate. there are some digits remaining, but not displaying in our parameter. so it is very close to, but not equal to value. Answers depend on accuracy.
 
It knows accurately -- you probably just have it set to display rounded off to a lower precision [fewer decimal places, or lower-denominator fractions] than you want.  Look into the LUPREC and AUPREC System Variables, and in Dimension Styles, the Primery Units' Precision settings for both Linear and Angular Dimensions.
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