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AutoCAD 2D I Module 7

Drawing Lines Using Polar Coordinates

PREPARED BY

IAT Curriculum Unit

February 2011

© Institute of Applied Technology, 2011

ATM1020 –Auto CAD 2D-I

Module 7: Drawing Lines Using Polar Coordinates 2

Auto CAD Self-paced Learning Modules

AutoCAD 2D

Drawing Lines Using Polar Coordinates

Learning Outcomes: When you have completed the 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.

Module 7

AutoCAD Geometry Lesson

Angles

An angle is formed by two intersecting lines. A full circle is 360 degrees. AutoCAD defines zero degrees at 3:00 o’clock with the positive angle in the counterclockwise direction and a negative angle in the clockwise direction. Study the drawing below. The principles you will learn are used extensively in AutoCAD.

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Module 7: Drawing Lines Using Polar Coordinates 3

Angles - Continued

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Module 7: Drawing Lines Using Polar Coordinates 4

The Polar Coordinate System The Polar Coordinate System is used to draw lines using distance and an angle. All angles are measured starting at 0 degrees at 3:00 o’clock. The angles are positive in the counterclockwise direction and negative in the clockwise direction. See Figure 8-1.

In almost all cases, you would use the @ symbol in front of the distance and angle. The first number is the distance then the less than symbol, and next the angle either positive or negative. For example: @6<45 This means “from the last point, go 6 units at an angle of 45 degrees, positive, starting at 3 o’clock.

For example: @5<60 This means “from the last point, go 5 units at an angle of 60 degrees, positive, starting at 3 o’clock. The polar coordinate @5<300 would mean the same to AutoCAD

AutoCAD User “Must Know” No. 10-1

AutoCAD measures angles starting at 3:00 o’clock. This is zero degrees. Positive angles are in the counterclockwise direction and negative angles are in the clockwise direction. The start point can be changed as you will see in the future module. It is important to leave it set in the default setting while doing lab exercises in the AutoCAD Modules.

Figure 8-1 The Polar Coordinate System

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Module 7: Drawing Lines Using Polar Coordinates 5

Using the Polar Coordinate System

Points A-B B-C C-D D-E E-F F-G G-H

Units 3 2 2 1.5 1 2 1.5

Command: LINE Specify first point: 2.5,4.5 (Start with a absolute cartesian coordinate.) Specify next point or [Undo]: @3<0 (A to B is a horizontal line which is zero degrees.) Specify next point or [Undo]: @2<90 (B to C is a vertical line at 90 degrees.) Specify next point or [Close/Undo]: @2<45 (C to D is 45 degrees positive.)

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Module 7: Drawing Lines Using Polar Coordinates 6

Using the Polar Coordinate System - Continued

Specify next point or [Close/Undo]: @1.5<100 (D to E.) Specify next point or [Close/Undo]: @1<180 (E to F is a horizontal line at 180 degrees.) Specify next point or [Close/Undo]: @2<225 (F to G.) Specify next point or [Close/Undo]: @1.5<165 (G to H.) Specify next point or [Close/Undo]: C (Use Close to finish.) Specify next point or [Close/Undo]: Command:

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Module 7: Drawing Lines Using Polar Coordinates 7

Object Snap Modes for all Objects

Modes Abbreviations Icon Marker The AutoCAD Object

Intersection

Int

X

AutoCAD User Tip 10-1

When you are entering a coordinate, either a polar coordinate or a Cartesian coordinate can be used. The two different systems can also be mixed in the same command. Use the one that works best for you.

Command: LINE Specify first point: 4,4 Specify 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 Command: LINE Specify first point: END of PICK 1 Specify next point or [Undo]: @1<180 Specify first point: END of PICK 2 Specify next point or [Undo]: Command: LINE Specify first point: END of PICK 3 Specify first point: END of PICK 4 Specify first point: END of PICK 5 Specify first point: END of PICK 6 Specify first point: Command: CIRCLE Specify center point for circle or [3P/2P/Ttr {tan tan radius}]: INT of PICK 7 Specify radius of circle or [Diameter]<0.5000>: D Specify diameter of circle <1.0000>: 1

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Module 7: Drawing Lines Using Polar Coordinates 8

Instruction:

1. Setup the layers using the Layering Scheme above. 2. Draw the object shown below. 3. You should not have any construction objects for this lab. 4. Check your drawing with the key.

Lab Exercise 8-1 Time Allotted: 30 min.

Drawing Specifications Name Template Units Text Style Font AutoCAD 2D Lab 8-1 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 Lineweight

Construction Objects Construction 253 N/A N/A

All Objects Object Red N/A N/A

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Module 7: Drawing Lines Using Polar Coordinates 9

Instruction:

1. Setup the layers using the Layering Scheme above. 2. Draw the object shown below. 3. You should not have any construction objects for this lab. 4. Check your drawing with the key.

Lab Exercise 8-2 Time Allotted: 30 min.

Drawing Specifications Name Template Units Text Style Font AutoCAD 2D Lab 8-2 Module Template A3 Millimeters N/A N/A

Note: Color, Linetype and Lineweight are all ‘ByLayer’ unless otherwise instructed.

Layering Scheme

Objects on Layer Name Color Linetype Lineweight

Construction Objects Construction 253 N/A N/A

All Objects Object Red N/A N/A