Hi

Can you help me please with this question :

ABC is a triangle where the point D is on Bc such that BAD = 60 , B=20 , AB = CD ...

Can you tell me ACB = ?????

(Crying)

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- August 28th 2010, 12:14 PMOnlyMathPlease help to find the angle
Hi

Can you help me please with this question :

ABC is a triangle where the point D is on Bc such that BAD = 60 , B=20 , AB = CD ...

Can you tell me ACB = ?????

(Crying) - August 28th 2010, 04:33 PMSoroban
Hello, OnlyMath!

I did a lot of trig and came with a surprisingly simple answer.

I suspect that there is an elegant geometric solution . . . somewhere.

Quote:

is a triangle where the point is on

. . such that: .

Find

Code:`B`

o

* *

* 20 *

* * D

a * 100 o

* * 80 * a

* 60 * x *

* * @ *

A o * * * * * * * o C

We have: .

Let

.[1]

.[2]

Equate [1] and [2]:

. .

. .

. .

. .

. .

. . . . . . .

Therefore: .

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Fascinating!

is isosceles: .

Also, is isosceles: .

Is there a more direct way to derive those facts?