KC1 Q36: Bridge

ok, first thing's first:
https://www.google.com/images?q=drawbrid ... 49&bih=704

Ok got it. 30-60-90 triangles. find the side of the two. Very confusing problem that has nothing to do with the problem. Had they said clearance width is X and what is X. I think I could've solved this.

[quote="Geva@MasterGMAT"]ok, first thing's first:
https://www.google.com/images?q=drawbrid ... 49&bih=704[/quote]

yellowho wrote:Wow, I don't even know what a drawbridge is or what I'm looking for in this diagram/problem:

Now, what you're looking for is marked in the diagram - the distance between the two tips of the bridge parts after they are drawn to 60 degrees angle

In order to know that, you need to know how much these tips extend horizontally from the bridge's sides. Drop a height from the tips of the bridges back to the ground, creating a 30:60:90 degree triangle on each end. Find the bottom leg of the right angle (the one opposite the top 30 degree angle), and subtract two of those from the bridge original 54 span.

In order to do that, you need to know the legnth of the bridge spans. If each span is x, then originally x+x-2 equaled 54 (-2 so as not to count the 2 meter overlap twice). 2x-2=54
2x=56
x=28.

when raised to 60 degrees, this span becomes the hypotenuse of our triangles, so the shorter leg will equal 28/2=14 (according to the 30:60:90 recycled ratio of 1:√3:2, the shorter leg will equal half of the hypotenuse).

Thus, the length between the tips is now the total 54-2*14 (one from either end) = 54-28 = 26.

yellowho wrote:Ok got it. 30-60-90 triangles. find the side of the two. Very confusing problem that has nothing to do with the problem. Had they said clearance width is X and what is X. I think I could've solved this.

Geva@MasterGMAT wrote:ok, first thing's first:
https://www.google.com/images?q=drawbrid ... 49&bih=704

heh, you beat me to it.