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of the triangle? Is there a formula?

2007-10-16 10:50:48 · 8 answers · asked by Anonymous in Science & Mathematics Mathematics

Sorry, I meant to say equilateral triangle. And this isn't homework help. It came up in an SAT practice test but the explanation wasn't good.
Thank you to those of you polite enough to answer.

2007-10-16 15:07:22 · update #1

8 answers

with an equally smart-**** response

2007-10-16 10:54:08 · answer #1 · answered by Super Chris 3 · 0 4

simply no there is no formula for all triangles.

Draw a circle. Then inscribe a triangle within that circle. Keeping one side move the opposite corner and you have another triangle (in the same circle; same radius) but with two very different sides.

In other words lots of different triangles can be inside the circle - with sides and different sum of lengths

Therefore you cant have a relationship between the radius and the triangle.

If you pick a specific triangle shape (eg equilateral triangle) you can get a relationship.

2007-10-16 11:50:36 · answer #2 · answered by Anonymous · 0 0

1 just use algebra...draw 3 lines from the center of the circle perpendicularily to the 3 sides, and solve for (3-r) + (4-r) = 5 r = 1

2016-05-22 23:55:11 · answer #3 · answered by aline 3 · 0 0

Hey!!..Northstars right!..Draw any old triangle* inside a given O.
Construct the diameter, say BD.(=2R)...now you have a cyclic quadlilateral. Now sinD=a/2R ..but A=pi-D ..so sinD=sinA (cyclic quad rules)..so sinA/a=sinB/b=sinC/c=1/2R. Is this a new theorem ..or did Euclid beat me to it by 2300 years??
* notation applies for triange inscribed within semicircle, need to cahange notation slightly for whole circle but basic idea's the same..need a diagram!

2007-10-16 13:14:07 · answer #4 · answered by alienfiend1 3 · 0 0

Given a circle with an inscribed triangle

Let
a, b, c = length of sides of triangle
R = radius of circumcircle

By the Law of Sines we have:

a/sinA = b/sinB = c/sinC = 2R

2007-10-16 10:54:48 · answer #5 · answered by Northstar 7 · 3 0

If the triangle is an equilateral one, r = (length of the side)/cos30

2007-10-16 10:55:38 · answer #6 · answered by Elle Kay 3 · 0 0

Sorry but I cant answer that question! I AM 10! Oww...My brain hurts! lol but usually I am really smart at math but not that! Oww...

2007-10-16 10:54:24 · answer #7 · answered by Gabe S 2 · 0 2

it'll be the height of the triagle. i'm not sure what measurements you have though.

2007-10-16 10:54:11 · answer #8 · answered by Anonymous · 0 2

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