Little explorations with HP calculators (no Prime)

03302017, 05:47 PM
(This post was last modified: 03302017 07:55 PM by Gerson W. Barbosa.)
Post: #78




RE: Little explorations with the HP calculators
(03302017 12:26 PM)Dieter Wrote:(03292017 06:15 PM)Han Wrote: So \(\angle BED\) , \(\angle BDE \), \( \angle CDE \) and \( \angle AED \) should be the only angles whose measure you cannot determine directly from the properties mentioned. What if you set up an appropriate system of equations involving these angles? That's what I'd done too, but the solution is very simple, I realize now. No need to solve any linear system. u = 72 v = 90 x = 60 y = 51 Explanation later. Gerson. PS: From E draw a perpendicular line to line AB, which intercepts it at F. Now we have two similar righttriangles: BEF and EFD. Angle DEF = angle EBF = 18 degrees, as we already know. Angle BDE, which you have named 'u' is its complement, 72 degrees. Finally, angle EDC, or your 'x', can be easily determined as 180  72  48 = 60 degrees. PPS: Please do not consider this. Without any grounds I had assumed angle BED was a right angle. Fooled by my own drawing... 

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