## Wednesday, January 27, 2010

### Problem 422: Triangle, 24, 30 degree, Angle, Congruence

Proposed Problem
Click the figure below to see the complete problem 422 about Triangle, 24, 30 degree, Angle, Congruence.

Complete Problem 422

Level: High School, SAT Prep, College geometry

1. This comment has been removed by a blog administrator.

2. Is the answer 48 degrees????

3. The answer is not 48 degrees

4. with the formula siny=sin(180-y) and the sine rule in ABD and BDC
sin24.sin(150-x)=sin30.sinx
sin(150-x)=sin(30+x)=sin30.cosx+cos30.sinx
after substitution and division by cosx
we have
tanx=sin30.sin24/(sin30-sin24.cos30)=tan54
x=54
.-.

5. Here goes again:

http://img218.imageshack.us/img218/4855/solg.png

Antonio: i can't directly copy a link when posting here, why? also, do you have any mail so that i can make you some questions?

6. Ale:
The HTML for a basic link looks like this:
< a href="http://URL">TEXT< /a>

This text will be highlighted, and when clicked on, the browser window will go to the address specificed by the URL.

My email address is on the web pages.

7. Problem 422
Forming an equilateral triangle ABΕ (D is an interior point of triangle ABE). Then < AEB = 60 = 2.30 = 2.ACB so E is circumcenter of triangle ABC.Therefore AB=BE=AE=EC=DC and
<EAC=36=<ECA, <EDC=72 so <DEA=<DAE=36 then AD=DE. Is triangle ABD=triangle EBD
So <DBA=<DBE=30. Therefore <BDC=x=30+24=54.
APOSTOLIS MANOLOUDIS 4 HIGH SHCOOL OF KORYDALLOS PIRAEUS GREECE