MathematicsChapter 8: Application of Trigonometry
Two Angles / Lighthouse
Two observers, same height object, two elevations: write tan for each and subtract distances if they are on the same line.
Learning objectives
- Define and explain two angles / lighthouse.
- Apply two angles / lighthouse to a focused FBISE question.
- Check the answer for correct terms, evidence, working, and units.
Definition
Two observers, same height object, two elevations: write tan for each and subtract distances if they are on the same line. Name the right triangles before you write numbers.
Where / symbols
- Two Angles / Lighthouse
- Two observers, same height object, two elevations: write tan for each and subtract distances if they are on the same line. Name the right triangles before you write numbers.
Relationship
- h = d tan theta
Overview
Learn the idea, then use it:
Core Understanding
Two observers, same height object, two elevations: write tan for each and subtract distances if they are on the same line. Name the right triangles before you write numbers.
Examples one tan per triangle · elevation from horizontal up · h = d tan theta · TWO ANGLES / LIGHTHOUSE: Two observers, same height object, two elevations: write tan for each and subtract distances if they are on the same lin
Exam Application
State the correct term, connect it to the chapter rule or evidence, and use a clear example or calculation.
Examples Define first · Show the rule or evidence · Check units, labels, and conclusion
WHAT — TWO ANGLES / LIGHTHOUSE
Two observers, same height object, two elevations: write tan for each and subtract distances if they are on the same line. Name the right triangles before you write numbers.
HOW — Use the idea
Identify what is given, select this topic's rule or evidence, apply it one step at a time, and check the result.
In simple words
Do not merge two angles / lighthouse with a neighbouring idea that uses a different definition, rule, or method.
Key points
- one tan per triangle
- elevation from horizontal up
- h = d tan theta
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.Two Angles / Lighthouse
Sticky Notes · Quick Revision
Core Idea
- Two observers, same height object, two elevations: write tan for each and subtract distances if they are on the same line.
Key Points
- one tan per triangle
- elevation from horizontal up
- h = d tan theta
Simple Check
- Explain two angles / lighthouse in your own words and connect it to one chapter example.
How to Answer
- Define the idea, show the main rule or evidence, apply it, and check the final statement.
Common Mistake
- Do not merge two angles / lighthouse with a neighbouring idea that uses a different definition, rule, or method.
FBISE Exam Tip
- Use the exact term, show working where needed, and include units or labelled evidence.
60-second revision
- Two observers, same height object, two elevations: write tan for each and subtract distances if they are on the same line.
- one tan per triangle
- elevation from horizontal up
- h = d tan theta
Did you understand this topic?
Your answer is saved with your learning record. It does not mark the topic as mastered.