pythagorean theorem word problem

[needhelp]

John traveled 12km North from his house. Then he traveled west and ended up 10km from his house. How far did John travel west?

 

[tkhunny]

I don't think so. x = distance west

12^2 + x^2 = 10^2

I dare you to solve for 'x' from the Real numbers.

 

[needhelp]

Original answer was 6, but I was wanting to make sure I did it correctly. Square root of 44, which is 6. Correct?

 

[stapel]

Original answer was 6, but I was wanting to make sure I did it correctly.

What did you "do"? Please review the earlier reply, and then provide specifics of your own solution method, starting from a description of the picture you drew. Thank you.

Square root of 44, which is 6. Correct?

Since 6² = 36, then sqrt[36] = 6. Since 44 > 36 (and, in particular, is not equal to 36), then sqrt[44] does not equal sqrt[36] = 6.

Eliz.

 

[needhelp]

12^2 + x^2 = 10^2

144 + x^2 = 100

x^2 = 144 - 100

x^2 = 44

x = 6.63

 

[stapel]

144 + x^2 = 100

x^2 = 144 - 100

How did you get this last equation? If you'd subtracted 144 from both sides, you would have gotten "x² = 100 - 144"...?

Thank you.

Eliz.

 

[tkhunny]

12^2 + x^2 = 10^2
144 + x^2 = 100
x^2 = 144 - 100
x^2 = 44
x = 6.63

Nice try, but no. If you state what it is you are doing, it is more difficult to wander off.

12^2 + x^2 = 10^2

Expanding the squares of constants

144 + x^2 = 100

Subtracting 144 from each side

x^2 = 100 - 144

See, you can't be tempted to write it backwards and magically come up with a positive value.