A tree needs to be staked with four wires. Each wire is attached to the trunk 3 feet above the ground, and then anchored to the ground 4 feet from the base of the tree. How much wire is needed for 7 trees?

Question

A tree needs to be staked with four wires.  Each wire is attached to the trunk 3 feet above the ground, and then anchored to the ground 4 feet from the base of the tree.  How much wire is needed for 7 trees?

jchick · Answer

This looks like the place to use the Pythagorean theorem. Solve for c to find the length of wire for one stake. 

c^2 = a^2 + b^2 
c^2 = 3^2 + b^2 
c^2 = 9 + 16 
c^2 = 25 
c = ?

jchick · Answer

Can you do it from here?

wolfadaskies · Answer

So.. 3^2 x 4^2 = 25
Sq. rt. 25= 5
5 x 7 = 14?
@jchick

jchick · Answer

Plug it in and see if it works! :)

jchick · Answer

c=5,−5

wolfadaskies · Answer

But with that answer, would we multiply it by 7- since it's asking how much wire there should be for 7 trees? @jchick

jchick · Answer

Yes however 5 * 7 doesn't equal 14.

jchick · Answer

It equals 35.

wolfadaskies · Answer

Oop- my bad, I didn't see that I made that typo.  Thank you for helping @jchick

jchick · Answer

No problem!

jchick · Answer

Oh just out of curiosity what type of math is this?

wolfadaskies · Answer

Geometry @jchick