Can you name the countries that have borders that form a 90 degree angle? by youppiinamerica

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Right Angle Countries Quiz

by youppiinamerica

Created Oct 8, 2010 in Geography
Game Plays 315

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	Just_Fold:	Oct 9th, 2010 at 01:22 GMT		1 point
	Please check spelling for Equatorial Guinea

	dancastro:	Oct 9th, 2010 at 01:37 GMT		4 points
	The idea is very interesting. There are some missing: the border USA-Canada has a right angle where the state of Minnesota and the provinces of Manitoba and Ontario meet (the border, which had followed the 49th parallel, turns due north), and there is another right angle in the border of New Mexico with the state of Chihuahua (Mexico). Libya has a right angle in the border with Sudan. I see no right angles in Chad. The ones in Oman and Mali aren't exactly of 90 degrees. If these corrections are made, it is indeed an excellent quiz.

	AdamBishop:	Oct 9th, 2010 at 01:38 GMT		2 points
	What about the Canada-US border? The Northwest Angle bends 90 degrees, although the actual bend is in a lake...

	youppiinamerica:	Oct 9th, 2010 at 01:50 GMT		1 point
	@dancastro-I looked at my atlas, and there is no right angle in the USA-Canada border, but definently on the USA-Mexico border. I think you're right about Chad, but I'm pretty sure about Oman and Mali, and I'll have to add Libya. Thanks for your corrections.

	jml1139:	Oct 9th, 2010 at 02:07 GMT		1 point
	libya?

	dancastro:	Oct 9th, 2010 at 02:21 GMT		2 points
	Sorry to appear pedantic, but I've just measured the angle of Oman (at the tripoint with Yemen and Saudi Arabia) and it's 85º 17'. The one of Mali (in the northern extreme of the country, in the border with Mauritania) is 84º 13'. The errors can be of a couple of minutes, but as you see the difference with the right angle is of several degrees. The only way to have an angle of exactly 90º is when the border follows a parallel and then a meridian or vice versa. The border Mali-Mauritania follows the parallel of 25º North but later it doesn't follow a meridian. The borders of Oman don't follow any, so only by a lucky chance they would form a right angle. And yes, I agree with AdamBishop, definitely there's a right angle in the US-Canada border.

	explodingtrees:	Oct 9th, 2010 at 02:35 GMT		1 point
	There's gotta be a right angle in here somewhere: http://thestrangemaps.blogspot.com/2010/10/79-cooch-behar-mother-of-all-enclave.html ;)

	bsd987:	Oct 9th, 2010 at 02:43 GMT		3 points
	@explodingtrees: There's definitely in the other mother-of-all-enclaves between Belgium and Netherlands, which both should be answers. That said, I wonder if any of the corners between the Vatican and Italy are right angles. http://www.wolfstad.com/2008/05/the-crazy-borders-of-baarle/

	bsd987:	Oct 9th, 2010 at 02:44 GMT		3 points
	So in short, missing USA, Canada, Belgium, Netherlands, and possibly Vatican City, Italy, Bangladesh, and India.

	finnoztoffee:	Oct 9th, 2010 at 03:13 GMT		2 points
	great idea for a quiz. good stuff.

	blan_mannan:	Oct 9th, 2010 at 03:25 GMT		1 point
	The far southeast corner of Colombia has a right angle in the town of Leticia, on the border with Brazil

	thedpr:	Oct 9th, 2010 at 03:55 GMT		3 points
	Vatican City's walls definitely meet at right angles at some places.

	thedpr:	Oct 9th, 2010 at 04:03 GMT		2 points
	Not sure Mali should be listed. The main n/s border with Mauritania is straight but not due north and south.

	hminion:	Oct 9th, 2010 at 05:05 GMT		5 points
	There are a bunch of others that, though small, are 90 degree angles. Off-hand I can think of Gambia (southern border with Senegal) and even Ghana (near the town of Wuru, the border with Burkina Faso does a funny little turn). In Indonesia, the northern part of the funky break in the line on Borneo with Papua New Guinea is also at a right angle. Not sure if you're counting this, but Uganda and Kenya's official border in Lake Victoria is a 90-degree angle against Tanzania's. In general, I like the idea. I just think it's one that can't be done completely right.

	deej:	Oct 9th, 2010 at 06:10 GMT		18 points
	We are all at home on a Friday night measuring maps with protractors - just like to point that out.

	Sjoerd:	Oct 9th, 2010 at 12:02 GMT		8 points
	I don't think this discussion is from the right angle...

	dancastro:	Oct 9th, 2010 at 17:24 GMT		4 points
	@deej: in fact, it was worse than that. I was still later on a Friday night (I'm one hour ahead of US Eastern Time) taking the latitude and longitude of points in the Oman-Saudi Arabia, etc., borders (with Google Earth), calculating their azimuths by the haversine formula (happily it's available online) and subtracting the azimuths to find the angle.

	bsd987:	Oct 9th, 2010 at 23:25 GMT		7 points
	@dancastro - I did not understand a single thing you said after "Google Earth"

	dancastro:	Oct 10th, 2010 at 01:10 GMT		1 point
	@bsd987: an azimuth (also called bearing) is a direction measured clockwise from north. For example, due east is 90º, due south is 180º, southwest is 225º, etc. If from a point you have two lines, one running in southwest direction (azimuth = 225º) and the other in southeast direction (azimuth = 135º), you subtract 225 - 135 = 90 degrees, so the angle between both lines is a right angle.

	tahitiwahini:	Jan 11th, 2011 at 00:44 GMT		1 point
	@dancastro in reference to your comment of Oct 9th, 2010 at 02:21 GMT: You said: "The only way to have an angle of exactly 90º is when the border follows a parallel and then a meridian or vice versa." It seems perfectly possible to me to have a right angle on a country's border where neither side of the angle is parallel to either a line of latitude or longitude. Granted because of the existence of latitude and longitude it's likely that a border will be parallel to one or the other but it's certainly not a requirement for having a right angle border.

	Thryduulf:	Oct 3rd, 2011 at 23:22 GMT		1 point
	Add in the missing countries (including Canada, see http://en.wikipedia.org/wiki/File:NORTHWEST_Angle.png) and you'll have a great quiz.