Perimeter Definition and 108 Threads

The vertices of a triangle are P(-3,1,2), Q(1,-3,-1) and R(3,-1,-1) -Verify that it is a right angled -Determine the area -Determine the perimeter -What are the coordinates of S(x,y,z) such that PQRS is a rectangle I'm not sure how to start to go about solving this problem. Could...

sometimes these Perimeter seminar talks become available at the stream media site http://streamer.perimeterinstitute.ca:81/mediasite/viewer/ Martin Bojowald (Penn State) is scheduled to speak Wednesday and Thursday of next week June 28 2:00 pm: Quantum Theory in Cosmology "Not only general...

In a few months Sabine Hossenfelder joins Perimeter Institute, as, I guess, a postdoc (dont know the structure there) What do you think about PI, it's intention, research and researchers (gossip welcome :biggrin:). [this post edited with helpful suggestion of hossi]

This quantum gravity workshop at the Perimeter Institute was really cool: http://www.perimeterinstitute.ca/activities/scientific/PI-WORK-2/ It was their first conference in the new building. I'm writing an issue of This Week's Finds about some things I learned that made me much more...

Is there any geometric figure whose calculation (area, perimeter, ...) involves the terms pi^2 or (pi^2-1) ?

To view some nice photos of Perimeter Institute's new building that were taken on its official opening day (Oct 2/2004) see: http://agar.ca/gallery/pi20041002 Perimeter Institute is located in Waterloo, Ontario, Canada. More specifically, the new facility is located in uptown Waterloo...

Could anyone direct me to an analytically correct algebraic formula for the Perimeter of an Ellipse based on either the eccentricity or the Semi-Major and Semiminor Axes other than the Elliptic Integral ? If so, how accurate will it be for relatively high eccentricities such as 0.9-1.0 ? Thanks.

I forgot the equation on how to solve for the area of an octagon. No information is given except that the total perimeter is 72 inches since we know that each side is 9-inch long. I looked up some stuff on the internet but it said we had to know the area from the middle of the shape to the...