TR-3B nuclear powered flying triangle - AboveTopSecret.com
Supposedly some group of Greys reportedly use triangle shaped craft. This is just something I've heard from a UFO guide, I'm not sure how reliable it is though. If the TR-3B is real, which I think it is then it would explain a large number of UFO sightings.

Bridgewater Triangle, page 1 - AboveTopSecret.com
In 1976 Coleman investigated reports of a large black dog that terrorized the town of Abington, which is inside the Triangle. A local fireman who owned two ponies had gone to check on his animals, and was horrified to see them lying dead on the ground with a huge black dog chewing on their necks. The dog disappeared into the woods.

Britain's Forgotten Triangle UFO Flap of March 1997 - AboveTopSecret.com
More Triangle UFO Sightings On March 13th 1997, thousands of miles across the Atlantic Ocean, the infamous Phoenix Lights UFO incident occurred. Meanwhile, back in the UK, MoD records also contain a sighting in Kingstanding, Birmingham, at 4am on March 18 1997. The witness reported seeing a 200ft triangle hover over his back garden.

The Black Triangle UFOs, page 1 - AboveTopSecret.com
Arbitrageur, there has been several discussions on the Greenville triangle sightings (bottom pics in your post). Many people, me included, are convinced these photos are hoaxes perpetrated by the same individual(s) in Greenville SC. Another Greenville triangle And one more [edit on 18-4-2010 by cripmeister]

One Year Before MH370 - Video Shows Orbs in Triangle Formation Circling ...
a reply to: b0kal0ka Good find, this MH370 thing has really fascinated me after seeing multiple professionals forensically analyze the footage and say it all looks legit.

Orbs Appear And Form Triangle On Live Cam. - AboveTopSecret.com
Below are a series of screenshots, showing 3 orbs appearing on live cam and forming a triangle off The New Jersey Coast last night. The orbs are at the top of the screen about two thirds across from the left. They should be quite clear to see. According to the time stamp at the bottom left of the screen, the whole episode takes place over 34 ...

Red dots in a triangle on body, page 3 - AboveTopSecret.com
The triangle lasted about two weeks total before it disappeared. If anyone has ever seen some of my responses here on ATS you probably surmise that I am a very superstitious person with a flare for "religious" indoctrinations, and that I am very fearful of demons; which is true by the way!

Mussolini formed a top secret UFO agency to investigate Triangle UFOs ...
In 1933, Italian leader Benito Mussolini allegedly formed a top secret UFO study group to investigate a flap of flying triangle UFOs being sighted all over Italy at the time. Active until 1940, the Italian government organization compiled many documents and pictures that were kept secret.

(Part 2 with Map) The Phoenix Lights - Laying To Rest The Myth
As stated in the OP, everyone who looked at the triangle of lights through binoculars or telescope, all saw individual lights with stars in between the lights. Nobody took pictures of, videos of, or viewed the alleged large black triangle through binoculars. There's just no proof of a large black triangle. originally posted by: dennisarends

3 small bruises in triangle pattern on arm - AboveTopSecret.com
I have three small bruises that are about the size of a dime on the underside of my arm. This isn't weird except that they are in a triangle pattern and I have no idea how I got them. In fact I wouldn't have even seen them unless my girlfriend hadn't had said something about them. I have pictures but don't know how to post them on here.