cos(c) = cos(a) cos(b) + sin(a) sin(b) cos(γ) | γ | angle opposite third side a | first side angular length b | second side angular length c | third side angular length

first side angular length | π/2 radians second side angular length | π/2 radians third side angular length | π/2 radians

angle opposite third side | 1.571 radians = 0.001571 krad (kiloradians) = 90° (degrees)

surface area | 1.5708 ≈ 12.5% of unit sphere surface area perimeter | 4.71239 ≈ 25% of unit sphere circumference