Calculating the Distance between the Feet of a Stepladder: Sin Rule & Pythagoras

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Homework Help Overview

The problem involves calculating the distance between the feet of a stepladder with given side lengths and an angle of inclination. The subject area includes trigonometry and geometry, specifically the application of the sine rule and Pythagorean theorem.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the use of the sine rule and Pythagorean theorem, with one participant attempting calculations based on an assumed right angle. Others question the validity of this assumption and suggest focusing on the given angle of 65 degrees.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the ladder's configuration. Some have identified potential errors in reasoning related to angle assumptions and diagram accuracy, while others are clarifying their understanding of the problem setup.

Contextual Notes

There is uncertainty regarding the angle at which the ladder opens, with participants debating whether it can be assumed to be 90 degrees. Additionally, there are questions about formatting in LaTeX, indicating a need for clarity in communication.

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Homework Statement


The two sides of a stepladder are of length 2m and 1.85m. When fully opened, the longer side is inclined at 65° to the horizontal. Find the distance apart of the feet of the step ladder.

Homework Equations


Sin Rule & Pythagoras?

The Attempt at a Solution


I had a go but I really think it's wrong.

HomeworkQues.jpg


[itex]\frac{2}{\sin90°} = \frac{b}{\sin65°}[/itex]

[itex]b = \frac{2}{\sin90°}\times \sin65°[/itex]

[itex]b = 1.81 (2d.p.)[/itex]

[itex]a^2 = 2^2 - 1.81^2 = 0.7239[/itex]

[itex]a = 0.85 (2d.p.)[/itex]

[itex]x^2 = 1.85^2 - 0.85^2 = 2.7[/itex]

[itex]x = 1.64 (2d.p.)[/itex]

[itex]l = 1.81 + 1.64 = 3.45m[/itex]


P.S. How do you do new lines in LaTeX?
 
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How do you know that the top angle is 90 degrees when it is fully opened? I think you have to stick with just the 65 degree angle and the leg lengths in order to find the distance.

Also, I don't know how to do new lines in LateX. I always just close the tex tag and start a new one.
 


I thought it would be 90 degrees because it says 65 degree to the horizontal.
 


You can't assume that the ladder opens up at 90 degrees (it doesn't actually).
 


I see what I did wrong. I got horizontal and vertical mixed up so I drew my diagram wrong.
 

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