Homework Help: pre calc

Posted by jim on Thursday, December 8, 2011 at 5:12pm.

EAch of 3 circles touch the other 2.
Circle A=radius 8cm
Circle B=radius 4cm
Circle c=radius 1cm
A triangle is formed by connecting the centers of the 3 traingles. Determine the largest angle for the traingle and which circle is the largest angle?
Also what is the area?
Please help really stumped!=[

pre calc - Reiny, Thursday, December 8, 2011 at 5:48pm
Wouldn't the triangle have sides of 12, 9, and 5 ?
So you given 3 sides,
Use the cosine law I just showed you in your previous post.

For the area use Heron's law
A = √(s(s-a)s-b)(s-c), were a,b, c are the sides and
s = (1/2)perimeter.
s = (12+9+5)/2 = 13
s-a = 13-12 = 1
s-b = 13-8 = 5
s-c = 13-5 = 8

area = √(13x1x5x8) = √520 = appr. 22.8 cm^2

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