SOLUTION: An obelisk is a tall, thin, four-sided monument that tapers to a pyramidal top. The most well-known obelisk to Americans is the Washington Monument on the National Mall in Washin

Algebra ->  Triangles -> SOLUTION: An obelisk is a tall, thin, four-sided monument that tapers to a pyramidal top. The most well-known obelisk to Americans is the Washington Monument on the National Mall in Washin      Log On


   

Question 238420: An obelisk is a tall, thin, four-sided monument that tapers to a pyramidal top.
The most well-known obelisk to Americans is the Washington Monument on
the National Mall in Washington, D.C. Each face of the pyramidal top of the
Washington Monument is an isosceles triangle. The height of each triangle is
55.5 feet, and the base of each triangle measures 34.4 feet. Find the length,
to the nearest tenth of a foot, of one of the two equal legs of the triangle.

I'm not sure how you calculate the length of a leg when they give you the length of the base, and the height of the triangle. I'm sure it's in the back of my head somewhere. I just need help getting it out of there and onto the paper.
Do I use the Pythagorean Theorem?
Like, a+b=c but with the squares in position?

THANKS! (:
- Kendall
9th Grader
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


Yes, Pythagoras is the one to use. But remember, when you construct the altitude of the isosceles triangle, it bisects the base. So the right triangle you want to calculate has legs that are the slant height of the pyramid which is the height of the isosceles triangle face, and one-half of the base measurement. Then the hypotenuse is one of the equal legs of the isosceles triangle.




John