What is quadrantal triangle in spherical trigonometry?

Answer 1

It's an equilateral triangle whose legs are all 90-degree arcs.

Here's a quadrantal triangle on the earth:

-- Start at the north Pole.

-- Draw the first side, down along the north 1/2 of the Prime Meridian to the equator.

-- Draw the second side westward along the equator, to 90 degrees west longitude.

-- Draw the third side straight north, back up to the north Pole.

Each side of the triangle is 90 degrees, each interior angle is also 90 degrees,

and the sum of its interior angles is 270 degrees.

Pretty weird.