Hallo Steffen,
1000 yds = 914,4 Meter
445 Fuß = 135,63600 Meter
135,6     x
----- = -----
914,4    1000
     135,6 * 1000
x = ------------ = 148m
        914,4
GF in ° = arctan(x/1000) = 8,4°