Lecture Notes: Scale Factor for Enlargement and Reduction

Introduction

• Speaker: Mr. Bars
• Topic: Unit 7, Sections 1 & 2: Scale Factor
  • Focus on enlargement and reduction

Scale Factor for Enlargement

• Example:
  • Original Image: 6x4 picture
  • Enlarged Image: 12x8 picture
• Objective:
  • Find the scale factor needed to enlarge the original image.

Formula for Scale Factor

• Scale Factor = (Scale Diagram) / (Original)
• Corresponding Sides: Match sides between the original and the scale diagram.
  • 6 corresponds to 12
  • 4 corresponds to 8

Calculating Scale Factor

• Pick corresponding sides: 12/6
• Scale Factor = 2
• Note: For enlargement, the scale factor is always greater than 1.

Scale Factor for Reduction

• Example:
  • Start with an original figure, then reduce it.

Differences in Reduction

• More complex due to potential orientation changes.
• Formula for Scale Factor:
  • Scale Factor = (Scale Diagram) / (Original)
  • Original is always the denominator.

Calculating Scale Factor

• Identify corresponding sides:
  • Example: 2.3 corresponds to a side
  • Example calculation: 4.1 (scale side) / 10.2 (original side)
• Calculation Result:
  • Decimal form: 0.401
• Note: Reductions will result in a scale factor less than 1.

Conclusion

• Understanding corresponding sides is crucial.

• Application of the formula ensures accurate scaling for both enlargements and reductions.

• Q&A: Encouraged for further clarity

• Reminder: More complex examples may require following the provided formula closely.

These notes should help you review the process of calculating scale factors for both enlargements and reductions. Feel free to reach out in class if you have any questions!