"Reverse Haversine" Formula implementation in Clojure

reverse-haversine.clj

; "Reverse haversine" to derive lat/long from start point, bearing (degrees clockwise from north), & distance (km)
; φ2 = asin( (sin φ1 ⋅ cos δ) + (cos φ1 ⋅ sin δ ⋅ cos θ) )
; λ2 = λ1 + atan2( sin θ ⋅ sin δ ⋅ cos φ1, cos δ − sin φ1 ⋅ sin φ2 )
; where φ is latitude, λ is longitude, θ is the bearing (clockwise from north), δ is the angular distance d/R; d being the distance travelled, R the earth’s radius

(defn reverse-haversine
  "Implementation of the reverse of Haversine formula. Takes one set of latitude/longitude as a start point, a bearing, and a distance, and returns the resultant lat/long pair."
  [{lon :lng lat :lat bearing :bearing distance :distance}]
  (let [R 6378.137 ; Radius of Earth in km
        lat1 (Math/toRadians lat)
        lon1 (Math/toRadians lon)
        angdist (/ distance R)
        theta (Math/toRadians bearing)
        lat2 (Math/toDegrees (Math/asin (+
                                         (* (Math/sin lat1) (Math/cos angdist))
                                         (* (Math/cos lat1) (Math/sin angdist) (Math/cos theta)))))
        lon2 (Math/toDegrees (+ lon1
                                (Math/atan2
                                 (* (Math/sin theta) (Math/sin angdist) (Math/cos lat1))
                                 (- (Math/cos angdist) (* (Math/sin lat1) (Math/sin lat2))))))]
    {:lat lat2 
     :lng lon2}))