Friday

August 22, 2014

August 22, 2014

Posted by **v** on Tuesday, June 8, 2010 at 7:03am.

- geometry -
**Reiny**, Tuesday, June 8, 2010 at 7:57ammake a diagram

Triangle ABC with AB=17, BC=8 and AC = 15

Did you realize that your triangle is right-angled, with angle C = 90° ?

let the points of contact of the circle be

D on BC, E on AC, and F on AB

Two properties we can use ...

1. The centre of the incscribed circle lies on the angle bisectors of the triangle, and

2. BF=BC , AE=AF, and DC = EC, by the tangent properties

let the radius be r,

since the 90° is bisected, DC = r

then BD= 8-r, and of course by #2 BF=8-r

then AF= 9+r and AE = 15-r

I see two similar triangles at the top, so

r/(9+r) = r/(15-r)

solve for r

**Related Questions**

GEOMETRY CIRCLES - 1. Ab is a chord of a circle with center o and radius 52 cm...

Geometry about the circles - 1. Ab is a chord of a circle with center o and ...

Geometry about the circles - 1. Ab is a chord of a circle with center o and ...

GEOMETRY CIRCLE - 1.An isosceles triangle with each leg measuring 13 cm is ...

GEOMETRY CIRCLES PLEASE - 1.An isosceles triangle with each leg measuring 13 cm ...

GEOMETRY CIRCLES PLEASE - HELP ME PLEASE. 1.An isosceles triangle with each leg...

geometry - An isosceles triangle has two 10.0-inch sides and a 2w-inch side. ...

Geometry - An isosceles triangle has two 10.0-inch sides and a 2w-inch side. ...

geometry - An isosceles triangle has two 10.0-inch sides and a 2w-inch side. ...

geometry - The radius of the inscribed circle is equal to twice the area of the ...