BIOL 1108 Edition 1st Lecture 3 Outline of Last Lecture I Precision and Accuracy II Types of error bias III Describing and graphing data Outline of Current Lecture I Traverse computations and map making sections 3 10 3 16 II Making a map III Closing the area IV Acceptable error V Adjusting azimuths VI Latitudes and departures VII Estimating area using Dot Grid Method VIII Estimating area using scaling triangle method Current Lecture I Traverse computations and map making sections 3 10 3 16 a Take spatial information and check quality of work i Compute the sum of the interior angles sum of interior angles degrees number of sides 2 180 1 If a traverse has 5 sides ii Sum of deflection angles 360 degrees b Determining interior angles Case 1 i North not involved ii Interior angle is less than 180 degrees iii Use horizontal distance with an engineer scale These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute II III IV V VI iv Convert frontsights to backsights 1 Interior angle larger smaller v Deflection angle difference between 180 and the interior angle c Case 2 i North is involved ii Interior angle is less than 180 degreed 1 Ex 360 degrees 310 degrees 50 degrees 40 degrees 50 degrees 90 degrees iii Interior deflection angles 180 degrees 1 Find the direction of deflection d Case 3 i Interior angle is great than 180 degrees obtuse 1 Convert frontsight to backsight to find interior ii North is not involved iii Difference between larger and smaller angle iv Deflection negative because the sum of the interior and deflection angles about any station point must be 180 degrees Making a map a Determine scale and choose a starting point b Align protractor with the paper s grid at starting point c Mark where Closing the area a Assign deflection with a direction and sign add them Acceptable error a Square root of the number of sides multiplied by the smallest angle that could be measured Adjusting azimuths a If the interior angles are less than the desired size add an equal amount to each and adjust the FS and BS accordingly b If the Latitudes and departures a Latitude the North South component of a course i Cos FS bearing x distance ii Sum should be 0 b Departure the East West component of a course i Sin ii Sum should be 0 c Use Pythagorean theorem to calculate error of closure if you don t close i Difference between latitudes and departures ii 1 total perimeter error of closure d Balancing i The correction value l sum of latitudes l x section side distance total perimeter VII VIII ii Balanced departure old latitude the correction values Estimating area using Dot Grid Method Estimating area using scaling triangle method a Size area 5 base x height