Math Is Fun Forum

Identity

Member

Registered: 2007-04-18

Posts: 934

Geometry: Show sum of angles is constant

I must be getting really rusty from not having done geometry in ages, but I'm stuck on how to prove that

in the following diagram:

(Note that the two angles x are equal)

Thanks

Last edited by Identity (2010-11-04 20:42:04)

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: Geometry: Show sum of angles is constant

hi Identity,

I've got a problem with this too.  Am I interpreting your diagram properly?  See below.

My software (Sketchpad) chooses vertex letters as I measure angles so I've had to letter as shown.

I'm taking your A as my ACB  and your B as AEB.

I've chosen x to be 12 in the first diagram and 14 in the second.

This gives firstly A + B = 65 but secondly A + B = 89.

I can show that B = A - 2x if that's any help.

Bob

Last edited by Bob (2010-11-05 07:23:30)

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob