Using Geometry to Make a RoofDate: 8/30/95 at 12:18:40 From: Jeff Robertson Subject: polyhedron I'm not a student but a wood worker with a question on solid geometry. I want to know how to calculate the angle on the sides of triangles in order to form a cone shaped (not round but angular) roof. I can calculate the base angle required to make the roof stand flat but can only use trial and error to get the angle that will make the sides come together. Date: 9/1/95 at 16:8:36 From: Doctor Ken Subject: Re: polyhedron Hello! Probably the best thing to do in this situation would be to find a triangle that contains your angle, and then try to figure out everything about the triangle. For instance, you find a triangle that contains the angle in question, then you figure out what the lengths of the three sides are, and you use trigonometry to figure out the angle you want. Or you can find the correct triangle, and measure the non-base angle of it (since it's isosceles). Can you get it now? I'd probably use the triangle made of the three following points: the center of the base of the cone, and the two points where the cone hits the edges of the cone perpendicularly. Then the two base angles of this triangle will be the angles you're looking for. - Doctor Ken, The Geometry Forum |
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