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SL8 07-03-2008 00:14

Homework help?!
 
1 Attachment(s)
Attachment 6412
Does anyone know how to find the diameter? It appears the lack of sleep is getting to me.
Chord BD=8, and minor arc BA=60 degrees

s_forbes 07-03-2008 00:16

Re: Homework help?!
 
If I remember geometry, BD is perpendicular to BA, so the diameter (DA) is 8/(cos(30))

Mike Schreiber 07-03-2008 00:26

Re: Homework help?!
 
To confirm his answer in a complicated round about way:

Line Seg BC would create an iscoceles triangle because two sides are equal to the radius. Using laws of sine
8/sin (120) = r/sin30
therefore
d=2(8sin(30)/sin(120))
If you evaluate you get the same number approximately 9.237 or
16/(sqrt(3) or rationalized 16sqrt(3)/3

Hope I helped haha

SL8 07-03-2008 00:27

Re: Homework help?!
 
Quote:

Originally Posted by s_forbes (Post 714005)
If I remember geometry, BD is perpendicular to BA, so the diameter (DA) is 8/(cos(30))

Thanks, I read what you said and had one of those slow.... ohhh yeah moments.

rpgcubed 21-03-2008 10:16

Re: Homework help?!
 
Another much simpler way is to form a 30-60-90 triangle BDA which allows you to find DA by dividing the segment BD by 2, and then times that by root 3 to find the length BA, which is the diameter.


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