Math Problem Statement

A slanted ladder, 𝑥 unit long, has its top resting on a vertical wall. Suppose the bottom of the ladder (resting on the horizontal ground) is shifted 14 units to the wall, then top of the ladder will move 8 units up the wall. Suppose instead that the bottom of the ladder is shifted 21 units away from the wall, then top of the ladder will move 27 units down the wall. How long is the ladder?

Solution

Let's set up the problem with two different right triangle configurations created by the ladder as it shifts. Let:

  • xx be the length of the ladder (hypotenuse in both cases).
  • In the first case, when the ladder is shifted so that the bottom is 14 units closer, let the height of the ladder on the wall be yy.
  • In the second case, when the ladder is shifted 21 units further away, let the height of the ladder be y27y - 27.

We have two equations based on the Pythagorean theorem from each configuration:

Equation 1

When the bottom of the ladder is 14 units closer: x2=(14)2+(y+8)2x^2 = (14)^2 + (y + 8)^2 Simplifying: x2=196+(y+8)2x^2 = 196 + (y + 8)^2

Equation 2

When the bottom of the ladder is 21 units further away: x2=(21)2+(y27)2x^2 = (21)^2 + (y - 27)^2 Simplifying: x2=441+(y27)2x^2 = 441 + (y - 27)^2

Now we have two equations:

  1. x2=196+(y+8)2x^2 = 196 + (y + 8)^2
  2. x2=441+(y27)2x^2 = 441 + (y - 27)^2

Since both expressions are equal to x2x^2, we can set them equal to each other:

196+(y+8)2=441+(y27)2196 + (y + 8)^2 = 441 + (y - 27)^2

Expanding and Simplifying

Expanding each squared term: 196+y2+16y+64=441+y254y+729196 + y^2 + 16y + 64 = 441 + y^2 - 54y + 729

Combine like terms: 260+y2+16y=1170+y254y260 + y^2 + 16y = 1170 + y^2 - 54y

Cancel y2y^2 from both sides: 260+16y=117054y260 + 16y = 1170 - 54y

Bring terms involving yy to one side: 70y=91070y = 910

Solve for yy: y=13y = 13

Substitute yy to Find xx

Now, substitute y=13y = 13 into one of the original equations to find xx. Using Equation 1:

x2=196+(13+8)2x^2 = 196 + (13 + 8)^2 x2=196+212x^2 = 196 + 21^2 x2=196+441x^2 = 196 + 441 x2=637x^2 = 637 x=63725.24x = \sqrt{637} \approx 25.24

Conclusion

The length of the ladder is approximately 25.24 units.

Would you like further clarification on any part of this solution?

Here are five related questions that expand on this information:

  1. What would happen if the ladder was moved an additional distance from the wall?
  2. How would the Pythagorean theorem apply if the wall or ground was not perpendicular?
  3. Could we solve this using trigonometric identities for angles in each configuration?
  4. What if we knew the initial distance of the ladder from the wall before it was shifted?
  5. How would the solution change if the wall and ground formed an acute angle?

Tip: When solving problems with shifting distances, set up equations based on each scenario to find common variables using substitution or elimination.

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Math Problem Analysis

Mathematical Concepts

Geometry
Right Triangle
Pythagorean Theorem

Formulas

Pythagorean theorem: a^2 + b^2 = c^2
Algebraic manipulation to solve simultaneous equations

Theorems

Pythagorean theorem

Suitable Grade Level

Grades 9-12