The fireman's problem (optimization)

**A fence ***a* feet high is *b* feet from a high burning building. Find the length of the shortest ladder that will reach from the ground across the top of the fence to the building.

I have the picture set up and now I'm stuck. I know that I have to express the ladder in terms of x and I'm pretty sure that it involves similar triangles. Thanks.

Re: The fireman's problem (optimization)

i had the same question in my study guide :/ i couldn't get the answer :S can u explain more deeply?