MIRROR command in AutoCAD - Cell-by-Cell Formula Trace

Sample Data

Coordinates of two objects before applying the MIRROR command in AutoCAD.

Cell	Value
A1	Object ID
B1	X Coordinate
C1	Y Coordinate
A2	Obj1
B2	2
C2	3
A3	Obj2
B3	5
C3	7

Formula Trace

MIRROR(Object Coordinates, Mirror Line)

Step 1: Select Object Obj1 at (2,3)

Step 2: Define Mirror Line (vertical line x=4)

Step 3: Calculate mirrored X for Obj1: x' = 2*4 - 2 = 6

Step 4: Y coordinate remains the same: y' = 3

Step 5: New coordinates for Obj1 after mirror: (6,3)

Step 6: Repeat for Obj2 at (5,7)

Step 7: Calculate mirrored X for Obj2: x' = 2*4 - 5 = 3

Step 8: Y coordinate remains the same: y' = 7

Step 9: New coordinates for Obj2 after mirror: (3,7)

Cell Reference Map

    A       B       C
1 Object  X Coord  Y Coord
2 Obj1    2       3
3 Obj2    5       7

Mirror line: vertical at x=4
Arrows: Obj1 (2,3) -> (6,3), Obj2 (5,7) -> (3,7)

The original object coordinates in columns B and C are used to calculate mirrored positions across the vertical mirror line at x=4.

Result

    A       B       C
1 Object  X Coord  Y Coord
2 Obj1    6       3
3 Obj2    3       7

Mirrored coordinates after applying MIRROR command across x=4

The table shows the new coordinates of the objects after mirroring across the vertical line x=4. X values are reflected, Y values stay the same.

Sheet Trace Quiz - 3 Questions

What is the new X coordinate of Obj1 after mirroring across the line x=4?

A 4

B 6

C 2

D 3

Key Result

MIRROR command reflects object coordinates across a defined mirror line by calculating new positions symmetrically.

Practice

1. What does the MIRROR command do in AutoCAD?

easy

A. Creates a flipped copy of selected objects

B. Deletes selected objects permanently

C. Rotates objects around a point

D. Scales objects to a new size

Solution

1. Step 1: Understand the MIRROR command purpose

   The MIRROR command is used to create a flipped copy of selected objects across a mirror line.

2. Step 2: Compare options with command function

   Only Creates a flipped copy of selected objects describes creating a flipped copy, which matches the MIRROR command's function.

3. Final Answer:

   Creates a flipped copy of selected objects -> Option A

4. Quick Check:

   MIRROR = flipped copy [OK]

Hint: MIRROR flips objects like a reflection [OK]

Common Mistakes:

• Confusing MIRROR with DELETE command
• Thinking MIRROR rotates objects
• Assuming MIRROR scales objects

2. Which of the following is the correct syntax to start the MIRROR command in AutoCAD?

easy

A. MIRR

B. MIRROR

C. MIRRORR

D. MIR

Solution

1. Step 1: Recall the exact command name

   The correct command to start mirroring is MIRROR.

2. Step 2: Check each option for correctness

   Only MIRROR matches the full and correct command name; others are incorrect or invalid.

3. Final Answer:

   MIRROR -> Option B

4. Quick Check:

   Command syntax = MIRROR [OK]

Hint: Type full command MIRROR to avoid errors [OK]

Common Mistakes:

• Using incomplete command like MIR or MIRR
• Adding extra letters like MIRRORR
• Assuming abbreviations always work

3. You select a rectangle and use the MIRROR command with mirror line points at (0,0) and (0,5). You choose to keep the original objects. What will be the result?

medium

A. The rectangle is deleted and replaced by a flipped copy

B. Only the original rectangle remains, no copy created

C. A flipped copy of the rectangle across the vertical line x=0, plus the original rectangle

D. A rotated copy of the rectangle around point (0,0)

Solution

1. Step 1: Identify mirror line and effect

   The mirror line is vertical at x=0, so the rectangle will be flipped horizontally across this line.

2. Step 2: Consider the option to keep original objects

   Choosing to keep originals means both the original and flipped copy will appear.

3. Final Answer:

   A flipped copy of the rectangle across the vertical line x=0, plus the original rectangle -> Option C

4. Quick Check:

   Mirror line vertical + keep original = flipped copy + original [OK]

Hint: Mirror line flips; keep original means both appear [OK]

Common Mistakes:

• Thinking original is deleted when 'keep' is chosen
• Confusing mirror with rotation
• Ignoring mirror line orientation

4. You tried to mirror a circle but after entering the two mirror points, AutoCAD gave an error and did not create the mirrored object. What is the most likely cause?

medium

A. The two mirror points are the same point

B. The circle is locked and cannot be mirrored

C. You forgot to select the circle before starting MIRROR

D. The MIRROR command does not work on circles

Solution

1. Step 1: Analyze mirror line points

   If the two mirror points are the same, the mirror line is invalid (zero length), causing an error.

2. Step 2: Check other options

   Circles can be mirrored, and selection is required before command, but error after points means mirror line issue.

3. Final Answer:

   The two mirror points are the same point -> Option A

4. Quick Check:

   Mirror line must have two distinct points [OK]

Hint: Mirror line needs two different points [OK]

Common Mistakes:

• Assuming MIRROR can't work on circles
• Forgetting to select objects before MIRROR
• Ignoring mirror line validity

5. You want to create a symmetrical floor plan by mirroring half of the design along a horizontal axis at y=10, keeping both the original and mirrored halves. Which steps should you follow?

hard

A. Select half design -> ROTATE command -> pick center (0,10) -> rotate 180 degrees

B. Select half design -> MIRROR command -> pick mirror line points (0,10) and (5,10) -> choose 'No' to keep original

C. Select full design -> MIRROR command -> pick mirror line points (0,0) and (10,0) -> choose 'No' to keep original

D. Select half design -> MIRROR command -> pick mirror line points (0,10) and (5,10) -> choose 'Yes' to keep original

Solution

1. Step 1: Select the correct half and mirror line

   Select the half design to mirror and use a horizontal mirror line at y=10 by picking points (0,10) and (5,10).

2. Step 2: Choose to keep original after mirroring

   Choosing 'Yes' to "Erase source objects?" means the original objects are kept, so both the original and mirrored halves appear to form the symmetrical floor plan.

3. Final Answer:

   Select half design -> MIRROR command -> pick mirror line points (0,10) and (5,10) -> choose 'Yes' to keep original -> Option D

4. Quick Check:

   Mirror half + horizontal line + keep original = symmetrical plan [OK]

Hint: Pick mirror line, choose 'Yes' to keep original [OK]

Common Mistakes:

• Choosing 'No' deletes original, leaving only mirrored side
• Using ROTATE instead of MIRROR
• Selecting full design instead of half