8. Word Problems: Draw the Hidden Triangle
GED® Geometry: Right Triangles · preview lesson
Many right-triangle questions hide the triangle inside a real situation. Your job is to draw it.
Common right-triangle setups:
- A ladder against a wall: ladder = hypotenuse.
- A ramp: ramp surface = hypotenuse; rise and run = legs.
- A rectangle diagonal: diagonal = hypotenuse; length and width = legs.
- A map or grid distance: east/west and north/south moves are legs; straight-line distance is the hypotenuse.
Routine:
- Sketch the right angle.
- Label the legs and hypotenuse.
- Decide whether you are finding the hypotenuse (add) or a leg (subtract).
- Check units and reasonableness. The hypotenuse should be the longest side.
Worked example: a person walks 12 blocks east and 5 blocks north. Straight-line distance:
\[
\sqrt{12^2 + 5^2} = \sqrt{144+25} = \sqrt{169} = 13.
\]
Common mistake: adding the walking distances \(12+5=17\). That is the path walked, not the straight-line distance.
A rectangle is 7 by 24. What is the diagonal?
The diagonal is the hypotenuse: \(\sqrt{7^2+24^2}=25\).
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