Learning Outcomes:When you have completed this module, you will be able to:
1. Describe angle geometry and the Polar Coordinate System.2. Use the LINE command to draw lines using the Polar Coordinate System.
Geometry LessonAngles
An angle is formed by two intersecting lines. A full circle is 360 degrees. AutoCAD defineszero degrees at 3:00 o'clock with the positive angle in the counterclockwise direction and anegative angle in the clockwise direction. Study the drawings below. The principles you willlearn are used extensively in AutoCAD.
Using the principles you just learned, find the answers A to L in the figures shown below.Try to do the calculation in your head. The answers are on page 10-13.
The Polar Coordinate SystemThe Polar Coordinate System is used to draw lines using a distance and an angle from a knowncoordinate location. All angles are measured starting 0 degrees at 3:00 o'clock. The anglesare positive in the counterclockwise direction and negative in the clockwise direction. SeeFigure 10-1.In almost all cases, you would use the @ symbol in front of the distance and angle. The firstnumber is the distance, then the less than symbol, and next the angle either positive ornegative.
For example:
@6<45
This means "from thelast point, go 6 unitsat an angle of 45degrees, positive,starting at 3 o'clock".AutoCAD alwaysassumes positive asdefault. Therefore,you do not have toindicate positive.For example:
@5<-60
This means "from thelast point, go 5 unitsat an angle ofnegative 60 degreesstarting at 3:00o'clock". The polarcoordinate @5<300would mean the sameto AutoCAD.
Figure 10-1The Polar Coordinate System
AutoCAD measures anglesstarting 0 degrees at 3:00 o'clock.Positive angles are in thecounterclockwise direction andnegative angles are in the
clockwise direction. The start point can bechanged as you will see in a future module. It isimportant to leave it set in the default setting whiledoing lab exercises in the AutoCAD Modules.
Using the Polar Coordinate System - Part 1Workalong and calculate the angles and polar coordinates. Do not drawthe objects in AutoCAD.
Step 1 Study Object A shown below and the solutions for numbers 1 to 6.
Step 2 Find the answers for numbers 7 to 11. The answers are on page 10-15. Don'tlook at the answers until you think you have correctly solved each one.
Object A Solution:
1. Find the polar coordinate A TO B: @2<02. Calculate the first angle: 180 - 150 = 30 degrees3. Find the polar coordinate B TO C: @2<304. Copy the 30 degree angle to the next corner.5. Calculate the second angle: 180 - 110 = 70 degrees6. Add the two angles: 30 + 70 = 1007. Find the polar coordinate C TO D: @_____<_______8. Copy the angle 100 to the next corner.9. Calculate angle DD: DD = __________10. Find angle EE: EE = _________11. Find the polar coordinate D TO E: @_____<___...continued on page 10-6
Using the Polar Coordinate System - Part 1 - Continued
Step 3 Study Object B shown below and find the solutions for numbers 1 to 11. Theanswers are on page 10-15. Don't look at the answers until you think you have correctlysolved each number.
Object B Solution:
1. Find polar coordinate A TO B2. Calculate angle AA:3. Find polar coordinate B TO C4. Copy angle AA to the next corner5. Calculate angle BB6. Find angle CC7. Find polar coordinate C TO D8. Copy angle CC to the next corner9. Calculate angle DD10. Find angle EE11. Find polar coordinate D TO E
Step 4 Set layer Construction as thecurrent layer and then enter the commandsshown below.
Command: LSpecify first point: 2,5Specify next point or [Undo]: @4,0
(or @4<0)Specify next point or [Undo]: @2<90
(or @0,2)Specify next point or [Close/Undo]: @1<90
(or @0,1)Specify next point or [Close/Undo]: @-3,0
(or @3<180)Specify next point or [Close/Undo]: @-1,0
(or @1<180)Specify next point or [Close/Undo]: @1<-90
(or @0,-1)Specify next point or [Close/Undo]: C
(See Figure 4A.)Command: LSpecify first point: (end) of P1Specify next point or [Undo]: @1<180Specify next point or [Undo]: (end) of P2Specify next point or [Close/Undo]:Command: LSpecify first point: (end) of P3Specify first point: (end) of P4Specify first point: (end) of P5Specify first point: (end) of P6Specify first point:Command: C
Object to be Drawn
Figure Step 4A
Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: (int) of P7(Snapping to the intersection of the two construction lines.)
Specify radius of circle or [Diameter] <0.5000>: DSpecify diameter of circle <1.0000>: 1Command:
Step 5 Without entering a command, select the objects shown in Figure Step 5A and
10 - 11
while the objects are selected, pull down the layer list from the toolbar and click the nameObject. Click the graphic window and press Esc to clear the selected objects. Yourdrawing should now appear as Figure Step 5B.
Figure Step 5A
Figure Step 5B
CompletedDrawing
Step 6 Freeze layer Construction to display the finalobject. See Figure Step 6.
Figure Step 6Step 7 Save and close the drawing.
The Key Principles in Module 101. The Polar Coordinate System is used to draw lines using a distance and an angle from a
known coordinate location.2. When using the polar coordinates, AutoCAD measures angles starting 0 degrees at 3:00 o'clock.
3. When using polar coordinates, positive angles are measured counterclockwise andnegative angles are measured clockwise.
AutoCAD 2D Lab 10-1 Module Template A Inches N/A N/A
Note: Color, Linetype, and Lineweight are all < ByLayer < unless otherwise instructed.
Layering Scheme
Objects on Layer Name Color Linetype LineweightConstruction Objects
All ObjectsInstructions:
Construction
Object
253
Red
N/A
N/A
N/A
N/A
1. Setup the layers using the Layering Scheme shown above.2. Draw the object shown below using the layering scheme above. In this drawing,
lines are on layer Object and will display red.3. There are no construction objects.4. Check your drawing with the key. The key name is the same as the drawing
name shown above. If you have trouble doing this, redo Module 3.5. If you have any errors, correct your drawing.6. Turn layer Key off and freeze layer Construction.7. Save and close the drawing. Completed
Construction HintsDo your best to complete the labexercise drawing without using thefollowing hint(s). If you get stuckand can't complete it on your own,use the following hint(s) to help you.
Hint 1
Figure Hint 1
Hint 2 Draw the line from J to I by snapping to theendpoints as shown in Figure Hint 2.
Note: Color, Linetype, and Lineweight are all < ByLayer < unless otherwise instructed.
Layering Scheme
Objects on Layer Name Color Linetype LineweightConstruction Objects
All ObjectsInstructions:
Construction
Object
253
Red
N/A
N/A
N/A
N/A
1. Setup the layers using the Layering Scheme shown above.2. Draw the object shown below using the layering scheme above. In this
drawing, lines are on layer Object and will display red.3. There are no construction objects.4. Check your drawing with the key. The key name is the same as the
drawing name shown above. If you have trouble doing this, redoModule 3.
5. If you have any errors, correct your drawing.6. Turn layer Key off and freeze layer Construction.7. Save and close the drawing.
CompletedDrawing
POINTS A -B B - C C - D D - E E - F F - G G - H H - I I - J
Do your best to complete the lab exercise drawing without using the following hint(s). If you getstuck and can't complete it on your own, use the following hint(s) to help you.
Hint 1
Figure Hint 1
Object A Solution:
1. Find the polar coordinate A TO B:2. Calculate the first angle:3. Find the polar coordinate B TO C:4. Copy the 30 degree angle to the next corner.5. Calculate the second angle:6. Add the two angles:7. Find the polar coordinate C TO D:9. Calculate angle DD:10. Find angle EE:11. Find the polar coordinate D TO E:
Object B Solution:
1. Find polar coordinate A TO B2. Calculate angle AA:3. Find polar coordinate B TO C4. Copy angle AA to the next corner5. Calculate angle BB6. Find angle CC7. Find polar coordinate C TO D8. Copy angle CC to the next corner9. Calculate angle DD10. Find angle EE11. Find polar coordinate D TO E
