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Does the entire line lie in the plane?

Read the idea, work independently, then explain what changed.

TOPIC 01

Space vectors and solid geometry: mixed review

A mixed assessment: identify the method, justify it and revise your reasoning.

What you will be able to explain

  • Connect the chapter skills without relying on the order of the exercises.

Try it. Leave your reasoning visible.

Use one hint at a time. A correction explains what changed, not just the final answer.

01 / Standard#Your turn

Does the entire line lie in the plane?

X=(0,0,31)+s(1,−1,0),Π:x+y+z=31X=(0,0,31)+s(1,-1,0), \Pi:x+y+z=31
  • Use acute line/plane angles; normals must be nonzero and distances nonnegative.
Skills and prerequisite lessons

Working and explanation

BUILD THE REASONING

Hint 1
Use the dot product to connect coordinates with length or angle.
Hint 2
n·u=0 and the initial point is in the plane.
Worked solution
  1. Use the dot product to connect coordinates with length or angle.

  2. Apply the stated relation and retain its conditions.

    x+y+z=s−s+31=31x+y+z=s-s+31=31
  3. Direction parallelism plus an incident point proves containment.

The requested relation or conclusion is shown below.

ℓ⊂Π\ell\subset\Pi

Checks and common pitfalls: Direction parallelism plus an incident point proves containment.

Reasoning checklist · self / teacher assessment
  • State a valid definition or model and its assumptions.
  • Show the intermediate mathematical relations, not only the final claim.
  • Check exclusions, units or the interpretation of the result.

Think first. Reveal a hint when the class is ready.

Focus on one question

Teacher preparation and assessment

Question sequence

  • Ask students to name the relevant condition before calculating.

Board plan

  • Compare valid methods and annotate their conditions.

Anticipated thinking

  • A correct final value may still hide a missing assumption.

Assessment checklist

  • Check the method, conditions, reasoning and interpretation separately.

No sign-in. Work stays in this browser. Export before clearing browser data. Written reasoning is assessed with a checklist.

Curriculum and source notes ↗