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Find: AreaABCD [acres]
North D C course bearing length [ft] 0.50 0.67 1.00 1.35 Find the area of the polygon A B C D, in acres. [pause] In this problem, ---- o AB N80 45’E 250.71 o BC S5 22’E 147.66 o CD N85 13’W 257.04 o DA N3 26’W 85.43
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Find: AreaABCD [acres]
North D C course bearing length [ft] 0.50 0.67 1.00 1.35 Points A, B, C and D are shown. And the bearings and lengths of the ---- o AB N80 45’E 250.71 o BC S5 22’E 147.66 o CD N85 13’W 257.04 o DA N3 26’W 85.43
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Find: AreaABCD [acres]
North D C course bearing length [ft] 0.50 0.67 1.00 1.35 connecting courses, are provided in the data table. [pause] To solve this problem, --- o AB N80 45’E 250.71 o BC S5 22’E 147.66 o CD N85 13’W 257.04 o DA N3 26’W 85.43
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Find: AreaABCD [acres]
North D C course bearing length [ft] coordinate we’ll use the coordinate method for finding areas, where the area equals ---- o AB N80 45’E 250.71 method o BC S5 22’E 147.66 o CD N85 13’W 257.04 o DA N3 26’W 85.43
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Find: AreaABCD [acres]
Σ Area=0.5* {yi*(xi-1-xi+1)} i=1 coordinate method D C course bearing length [ft] one half times the absolute value of the sum of the product of the y coordinate of a point, times the difference between the x coordinates of the preceding point and the x coordinate of the subsequent points, for all n points. o AB N80 45’E 250.71 o BC S5 22’E 147.66 o CD N85 13’W 257.04 o DA N3 26’W 85.43
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Find: AreaABCD [acres]
Σ Area=0.5* {yi*(xi-1-xi+1)} i=1 coordinate method D C course bearing length [ft] x y Therefore we’ll have to solve for the x and y coordinates of Points A, B, C and D, using the given data. o AB N80 45’E 250.71 A Ax Ay o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD [acres]
Σ Area=0.5* {yi*(xi-1-xi+1)} i=1 coordinate method D C course bearing length [ft] x y Since no coordinates are given for any of the points, we’ll arbitrarily set Point A to the origin, ---- o AB N80 45’E 250.71 A Ax Ay o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD [acres]
y A x n Σ Area=0.5* {yi*(xi-1-xi+1)} D C i=1 course bearing length [ft] x y of an x-y coordinate system, where A X equals 0 feet, ---- o AB N80 45’E 250.71 A Ax Ay o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD [acres]
y A (0,0) x n Σ Area=0.5* {yi*(xi-1-xi+1)} D C i=1 course bearing length [ft] x y and A Y equals 0 feet. Next we’ll use the bearing and length values, --- o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD [acres]
y A (0,0) x n Σ Area=0.5* {yi*(xi-1-xi+1)} D C i=1 course bearing length [ft] x y given for the 4 courses, to determine the x and y coordinates for Points B, ---- o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD [acres]
y A (0,0) x D C course bearing length [ft] x y C and D. From trigonometry, we can equate the x value of Point B to --- o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD [acres]
Bx = Ax + LAB * sin (BAB) D C course bearing length [ft] x y the x value of Point A, plus the length of line segment A B, times sine of the bearing of course A B. o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD [acres]
Bx = Ax + LAB * sin (BAB) 0 [ft] D C course bearing length [ft] x y If we plug in the x coordinate of A, length A B, and the bearing of Course A B, the x coordinate of B equals, --- o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD [acres]
Bx = Ax + LAB * sin (BAB)= [ft] 0 [ft] D C course bearing length [ft] x y feet. [pause] We can find the y coordinate of Point B by adding the y coordinate of Point A to --- o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD [acres]
Bx = Ax + LAB * sin (BAB)= [ft] By = Ay + LAB * cos (BAB) 0 [ft] D C course bearing length [ft] x y to the length of line segment A B, times the cosine of the bearing of course A B, which equals, --- o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD [acres]
Bx = Ax + LAB * sin (BAB)= [ft] By = Ay + LAB * cos (BAB)= [ft] 0 [ft] D C course bearing length [ft] x y 40.30 feet. [pause] The coordinates for Points C and D are calculated the same way, --- o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD [acres]
Cx = Bx + LBC * sin (BBC) Cy = By - LBC * cos (BBC) Dx = Cx - LCD * sin (BCD) Dy = Cy + LCD * cos (BCD) C course bearing length [ft] x y as was coordinate B. We’ll plug in the x and y coordinate values from the previous point on the traverse, plus or minus --- o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD [acres]
Cx = Bx + LBC * sin (BBC) Cy = By - LBC * cos (BBC) Dx = Cx - LCD * sin (BCD) Dy = Cy + LCD * cos (BCD) C course bearing length [ft] x y the length between that Point and the previous Point, times, the sine or cosine of the bearing ---- o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD [acres]
Cx = Bx + LBC * sin (BBC) Cy = By - LBC * cos (BBC) Dx = Cx - LCD * sin (BCD) Dy = Cy + LCD * cos (BCD) C course bearing length [ft] x y of the course from the preceding point, to that point. [pause] o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD Bx = 247.45 [ft] By = 40.30 [ft]
Cx = Bx + LBC * sin (BBC) B Cy = By - LBC * cos (BBC) Dx = Cx - LCD * sin (BCD) Dy = Cy + LCD * cos (BCD) C course bearing length [ft] x y After plugging in the appropriate coordinate values, lengths and bearings, the coordinates of Point C and ---- o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD Bx = 247.45 [ft] By = 40.30 [ft]
Cx = Bx + LBC * sin (BBC) = [ft] B Cy = By - LBC * cos (BBC) = [ft] Dx = Cx - LCD * sin (BCD) = 5.12 [ft] Dy = Cy + LCD * cos (BCD) = [ft] C course bearing length [ft] x y and Point D are determined. [pause] Lastly, we’ll confirm the traverse closes ---- o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD Ax = Dx - LDA * sin (BDA) B Ay = Dy + LDA * cos (BDA)
course bearing length [ft] x y by calculating the coordinates of Point A. Using the coordinates of Point D, the length of D A, and the bearing ---- o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD Dx = 5.12 [ft] Dy = -85.28 [ft]
Ax = Dx - LDA * sin (BDA) B Ay = Dy + LDA * cos (BDA) D C course bearing length [ft] x y of Course D A, we calculate Point A is indeed located at, --- o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD Dx = 5.12 [ft] Dy = -85.28 [ft]
Ax = Dx - LDA * sin (BDA) = 0.00 [ft] B Ay = Dy + LDA * cos (BDA) = 0.00 [ft] D C course bearing length [ft] x y the origin, 0, 0. Which means the traverse closes, and doesn’t need to be corrected. o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD Dx = 5.12 [ft] Dy = -85.28 [ft]
Ax = Dx - LDA * sin (BDA) = 0.00 [ft] B Ay = Dy + LDA * cos (BDA) = 0.00 [ft] no correction D necessary C course bearing length [ft] x y Next we’ll set up a table to summarize the x and ---- o AB N80 45’E 250.71 A o BC S5 22’E 147.66 B Bx By o CD N85 13’W 257.04 C Cx Cy o DA N3 26’W 85.43 D Dx Dy
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Find: AreaABCD [acres]
Point x [ft] y [ft] y coordinate values for Points A, B, C and D, and we recall our equation for the area only involves --- A 0.00 0.00 North B 247.45 40.30 C 261.26 D 5.12 -85.28
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Find: AreaABCD [acres]
Σ Area=0.5* {yi*(xi-1-xi+1)} i=1 coordinate method Point x [ft] y [ft] these x, and y, coordinate values. Next we’ll add a column to the table, for the variable i. A 0.00 0.00 North B 247.45 40.30 C 261.26 D 5.12 -85.28
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Find: AreaABCD [acres]
Σ Area=0.5* {yi*(xi-1-xi+1)} i=1 coordinate method Point i x [ft] y [ft] Variable i corresponds to the iteration in the summation. --- A 1 0.00 0.00 B 2 247.45 40.30 C 3 261.26 D 4 5.12 -85.28
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Find: AreaABCD [acres]
Σ Area=0.5* {yi*(xi-1-xi+1)} i=1 coordinate method Point i x [ft] y [ft] [pause] To avoid confusion, the term y sub i, refers to --- A 1 0.00 0.00 B 2 247.45 40.30 C 3 261.26 D 4 5.12 -85.28
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Find: AreaABCD [acres]
Σ Area=0.5* {yi*(xi-1-xi+1)} i=1 coordinate method Point i x [ft] y [ft] the y coordinate of the Point whose value is i. For example, if i equals 2, then --- A 1 0.00 0.00 B 2 247.45 40.30 C 3 261.26 D 4 5.12 -85.28
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Find: AreaABCD [acres]
Σ Area=0.5* {yi*(xi-1-xi+1)} Example #1: i=1 if i=2, then coordinate method yi=40.30 [ft] Point i x [ft] y [ft] y sub 2 equals feet, as shown in the data table. [pause] As a second example, if i equals 1, ---- A 1 0.00 0.00 B 2 247.45 40.30 C 3 261.26 D 4 5.12 -85.28
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Find: AreaABCD [acres]
Σ Area=0.5* {yi*(xi-1-xi+1)} Example #1: i=1 if i=2, then coordinate method yi=40.30 [ft] Example #2: Point i x [ft] y [ft] if i=1, then then, x sub i minus 1, will equal x sub 0. But but there are no points ---- A 1 0.00 0.00 xi-1=x0 B 2 247.45 40.30 C 3 261.26 D 4 5.12 -85.28
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? Find: AreaABCD [acres] Σ Area=0.5* {yi*(xi-1-xi+1)} Example #1:
if i=2, then coordinate method yi=40.30 [ft] Example #2: Point i x [ft] y [ft] if i=1, then whose i value equals zero. In this case, we’ll loop back around ---- A 1 0.00 0.00 xi-1=x0 B 2 247.45 40.30 ? C 3 261.26 D 4 5.12 -85.28
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Find: AreaABCD [acres]
Σ Area=0.5* {yi*(xi-1-xi+1)} Example #1: i=1 if i=2, then coordinate method yi=40.30 [ft] Example #2: Point i x [ft] y [ft] if i=1, then and use the coordinates for i equals 4, which are the coordinates for Point D. A similar situation occurs for x sub i plus 1, --- A 1 0.00 0.00 xi-1=x0=x4 B 2 247.45 40.30 C 3 261.26 D 4 5.12 -85.28
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Find: AreaABCD [acres]
Σ Area=0.5* {yi*(xi-1-xi+1)} Example #1: i=1 if i=2, then coordinate method yi=40.30 [ft] Example #2: Point i x [ft] y [ft] if i=1, then when i equals 4. To avoid this confusion, we’ll add a row for i equals 0 and --- A 1 0.00 0.00 xi-1=x0=x4 B 2 247.45 40.30 Example #3: C 3 261.26 if i=4, then D 4 5.12 -85.28 xi+1=x5=x1
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Find: AreaABCD [acres]
Σ Area=0.5* {yi*(xi-1-xi+1)} i=1 Point i x [ft] y [ft] new row D 5.12 -85.28 A 1 0.00 0.00 and a row for I equals 5, which are just copies of coordinate data from rows i = 4 and i =1, respectively. Returning to our equation for area, --- B 2 247.45 40.30 existing rows C 3 261.26 D 4 5.12 -85.28 new row A 5 0.00 0.00
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Find: AreaABCD [acres]
Σ Area=0.5* {yi*(xi-1-xi+1)} i=1 Point i x [ft] y [ft] D 5.12 -85.28 A 1 0.00 0.00 there are 4 verticies to the closed traverse, so we’ll assign --- B 2 247.45 40.30 C 3 261.26 D 4 5.12 -85.28 A 5 0.00 0.00
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Find: AreaABCD [acres]
Σ Area=0.5* {yi*(xi-1-xi+1)} i=1 n=4 Point i x [ft] y [ft] D 5.12 -85.28 A 1 0.00 0.00 the value of n to equal 4. Next we’ll write out the summation equation --- B 2 247.45 40.30 C 3 261.26 D 4 5.12 -85.28 A 5 0.00 0.00
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Find: AreaABCD [acres]
y1*(x0-x2)+y2*(x1-x3) Area=0.5* +y3*(x2-x4)+y4*(x3-x5) Point i x [ft] y [ft] D 5.12 -85.28 A 1 0.00 0.00 for values of i ranging from 1 to 4. Then we’ll plug in the appropriate ---- B 2 247.45 40.30 C 3 261.26 D 4 5.12 -85.28 A 5 0.00 0.00
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Find: AreaABCD [acres]
y1*(x0-x2)+y2*(x1-x3) Area=0.5* +y3*(x2-x4)+y4*(x3-x5) Point i x [ft] y [ft] D 5.12 -85.28 A 1 0.00 0.00 values for x, and the appropriate values for y --- B 2 247.45 40.30 C 3 261.26 D 4 5.12 -85.28 A 5 0.00 0.00
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Find: AreaABCD [acres]
y1*(x0-x2)+y2*(x1-x3) Area=0.5* +y3*(x2-x4)+y4*(x3-x5) Point i x [ft] y [ft] D 5.12 -85.28 A 1 0.00 0.00 [pause] And the area of A B C D equals --- B 2 247.45 40.30 C 3 261.26 D 4 5.12 -85.28 A 5 0.00 0.00
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Find: AreaABCD [acres]
y1*(x0-x2)+y2*(x1-x3) Area=0.5* +y3*(x2-x4)+y4*(x3-x5) Area = 29,334 [ft2] Point i x [ft] y [ft] D 5.12 -85.28 A 1 0.00 0.00 29,334 feet squared. Since the problem asks to find the area in acres, we’ll divide this quantity by ---- B 2 247.45 40.30 C 3 261.26 D 4 5.12 -85.28 A 5 0.00 0.00
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Find: AreaABCD [acres]
y1*(x0-x2)+y2*(x1-x3) Area=0.5* +y3*(x2-x4)+y4*(x3-x5) Area = 29,334 [ft2] 1 acre Point i x [ft] y [ft] * 43,560 ft2 D 5.12 -85.28 A 1 0.00 0.00 43,560 square feet per acre, and the final area equals --- B 2 247.45 40.30 C 3 261.26 D 4 5.12 -85.28 A 5 0.00 0.00
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Find: AreaABCD [acres]
y1*(x0-x2)+y2*(x1-x3) Area=0.5* +y3*(x2-x4)+y4*(x3-x5) Area = 29,334 [ft2] 1 acre * Area = [acres] 43,560 ft2 0.673 acres. [pause]
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Find: AreaABCD [acres]
y1*(x0-x2)+y2*(x1-x3) Area=0.5* +y3*(x2-x4)+y4*(x3-x5) Area = 29,334 [ft2] 1 acre * Area = [acres] 43,560 ft2 0.50 0.67 1.00 1.35 When reviewing the possible solutions, ---
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Find: AreaABCD [acres]
y1*(x0-x2)+y2*(x1-x3) Area=0.5* +y3*(x2-x4)+y4*(x3-x5) Area = 29,334 [ft2] 1 acre * Area = [acres] 43,560 ft2 AnswerB 0.50 0.67 1.00 1.35 the answer is B.
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