Grade 9 · lesson 2 of 4

Apply a Stipulated Projection Relationship

Under the supplied model, projected width equals a constant divided by distance.

About 25 minutes, plus any extended practice

Download the grade pack

Supplied materials

  • Paper and a pencil, typed notes or a browser scratch area. Color names can replace colored supplies; drawn figures and timelines can replace performance.
  • Complete teaching inputs: For a supplied perspective model, projected width is constantK divided by distance. At distance2, width is24 units. What width does the same model give at distance4? Supplied candidates: (A) 11 units (B) 12 units (C) 13 units (D) 14 units.
  • Independent check: For a supplied perspective model, projected width is constantK divided by distance. At distance3, width is24 units. What width does the same model give at distance9? Supplied candidates: (A) 10 units (B) 7 units (C) 8 units (D) 9 units.

Learn the idea

Link a design’s purpose, representation and evidence. Prioritize required information, apply a stipulated projection model, construct an argument from visible features and organize a portfolio so a reviewer can trace revision decisions. Under the supplied model, projected width equals a constant divided by distance. Derive the constant from one complete observation, then use the new distance instead of assuming width changes additively.

Reason through the supplied case: The first observation gives K=24×2=48. The farther width is K/4=12. This inverse-distance projection is a stipulated simplified model, not a measured rule for every artwork or real-world camera.

This inverse-distance relationship is a simplified exercise model. It does not establish every camera’s behavior or the physical scale of an artwork from a description.

  1. Read the complete teaching inputs and mark the feature, rule or constraint being tested.
  2. Compare the model decision with one rejected candidate; state the visible evidence or calculation that distinguishes them.
  3. Solve the independent check and the three changed-input practice cases before reading feedback.
  4. Use width twenty-four at distance three to predict width at distance nine, showing the inferred constant.
  5. Check your artifact against these explicit criteria: The constant is seventy-two and the predicted width is eight units under the supplied model.
Worked example

See the method in action

For a supplied perspective model, projected width is constantK divided by distance. At distance2, width is24 units. What width does the same model give at distance4? Supplied candidates: (A) 11 units (B) 12 units (C) 13 units (D) 14 units. Model decision: 12 units. The first observation gives K=24×2=48. The farther width is K/4=12. This inverse-distance projection is a stipulated simplified model, not a measured rule for every artwork or real-world camera.

Your turn

Check your reasoning

Your answer is temporary and is not saved to an account. Download your current answer before leaving or reloading. Written work on paper or in another app stays in your own file.

Helpful tips
  • Under the supplied model, projected width equals a constant divided by distance.
  • This inverse-distance relationship is a simplified exercise model.
For a supplied perspective model, projected width is constantK divided by distance. At distance3, width is24 units. What width does the same model give at distance9?

Feedback appears here after you check. This is practice, not a graded school assessment.

See the answer and explanation

8 units

The first observation gives K=24×3=72. The farther width is K/9=8. This inverse-distance projection is a stipulated simplified model, not a measured rule for every artwork or real-world camera.

Take it further

New-input analysis: For a supplied perspective model, projected width is constantK divided by distance. At distance5, width is24 units. What width does the same model give at distance15? Supplied candidates: (A) 10 units (B) 7 units (C) 8 units (D) 9 units. Expected relationship: 8 units. The first observation gives K=24×5=120. The farther width is K/15=8. This inverse-distance projection is a stipulated simplified model, not a measured rule for every artwork or real-world camera. Create your own artifact: Use width twenty-four at distance three to predict width at distance nine, showing the inferred constant. Completion criteria: The constant is seventy-two and the predicted width is eight units under the supplied model.

Nothing here is saved to an account or sent to a teacher. The answer download includes your current choice and any checked feedback. It does not include choices from the separate More practice section. Download that section separately.

More practice: try new cases

Choose an answer for each problem. Explain your method on paper, then use the feedback to decide what to revisit.

More practice: try new cases
1. For a supplied perspective model, projected width is constantK divided by distance. At distance4, width is24 units. What width does the same model give at distance16?
Need a hint?
  • Under the supplied model, projected width equals a constant divided by distance.
  • This inverse-distance relationship is a simplified exercise model.
2. For a supplied perspective model, projected width is constantK divided by distance. At distance5, width is24 units. What width does the same model give at distance10?
Need a hint?
  • Under the supplied model, projected width equals a constant divided by distance.
  • This inverse-distance relationship is a simplified exercise model.
3. For a supplied perspective model, projected width is constantK divided by distance. At distance2, width is24 units. What width does the same model give at distance6?
Need a hint?
  • Under the supplied model, projected width equals a constant divided by distance.
  • This inverse-distance relationship is a simplified exercise model.

Your choices are temporary. Feedback appears after you check all the answers.

Nothing here is saved to an account or sent to a teacher. Keep your own notes or download them before leaving. The score describes these questions; it does not certify subject mastery.

Check the subject sources

These LifeStarter passages, scenarios and exercises are authored for this Academy with AI assistance and review. External resources keep their publishers’ terms. A grade label suggests a starting level; it does not establish alignment with your school’s complete requirements.