Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Topic: Three points on incircle
Replies: 5   Last Post: May 29, 2014 3:04 PM

 Messages: [ Previous | Next ]
 Peter Scales Posts: 192 From: Australia Registered: 4/3/05
Re: Three points on incircle
Posted: Apr 30, 2014 2:10 PM

>
> The next problem is as follows:
>
> Let A=[-1,-1], B=[1,-1]. Construct points D, E, F on
> the unit circle, such that line DE is parallel to the
> y-axis, and triples {B,E,F], {A,F,D} are collinear
> respectively.
>

Hi Avni,

Construct the unit circle and points A and B
Construct P(2/5,1/5) with OP=1/sqrt(5)
Circle centre O, radius OP meets ox in Q(1/sqrt(5),0)
Vertical thru Q meets unit circle at D and E,
with y = +- 2/sqrt(5)
Line AD meets unit circle at F(-sqrt(5)/3,-2/3)
B,E,F are collinear.

Regards, Peter Scales.

Date Subject Author
4/27/14 Avni Pllana
4/28/14 Peter Scales
4/28/14 Avni Pllana
4/30/14 Peter Scales
4/30/14 Avni Pllana
5/29/14 Avni Pllana