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
Sum of angles of a triangle to zero. For a spherical triangle, the sum of the angles is greater than 180° and can be up to 540°. Specifically, the sum of the angles is where "f" is the fraction of the sphere's area which is enclosed by the triangle. Note that spherical geometry does not satisfy several of Euclid's axioms (including the parallel postulate.) Angles between adjacent sides of a triangle are referred to as "interior" angles in Euclidean and other geometries. "Exterior" angles can be also defined, and the Euclidean triangle postulate can be formulated as the exterior angle theorem. One can also consider the