1 in 60 rule has 90 miles to his next waypoint. He is thus two miles to the left of that and thus the waypoint is 4/3 of a degree (2 × 60/90) to the right, or approximately 1° right. The pilot then adds these two to get 5° and flies 5° right of t his previous heading. One can also use the 1 in 60 rule to approximate distance from a VOR, by flying 90 degrees to a radial and timing how long it takes to fly 10 degrees (the limit of the course deviation indicator). The time in seconds divided by 10
Schwarz triangle function of the upper half plane. To see how to handle the case when an angle of Δ is a right angle, note that the inequality implies that if one of the angles is a right angle, say "a" = 2, then both "b" and "c" are greater than 2 and one of them, "b" say, must be greater than 3. In this case, reflecting the triangle across the side AB gives an isosceles hyperbolic triangle with angles /"c", /"c" and 2/"b". If 2/"b" ≤ /3, i.e. "b" is greater than 5, then all the angles of the doubled triangle are