FACTORS AND TABLES OF EQUIVALENTS USED IN FORESTRY 15 



Table 25. — Quarter girth; 1 equivalents in true girth, diameter, area, and volume, 

 United Stales measurement and metric system 



Quarter girth unit 



United States measurement 



Metric system 







In true girth = 10.16 cm. 













1 square foot per acre 





/ =0.118288 m2 per acre. 

 1=0.29230 m2 per hectare. 

 /= 0.036054 m3 per acre. 

 \=0.089092 m3 per hectare. 









1 A British unit used customarily in East Indian forestry, equivalent to about 1}4 diameters. The 

 converting factor from diameter to quarter girth would be -. or 0.7854. 



Table 26. — Natural trigonometric functions, by half degrees 



Degree 



Sin 



Cos 



Tan 



Degree 



Sin 



Cos 



Tan 



Degree 



Sin 



Cos 



Tan 



o / 



30 



0. 0087 



1. 0000 



0. 0087 



15 



30 



0. 2672 



0. 9636 



0. 2773 



o 



30 



30 



0. 5075 



0. 8616 



0. 5890 



1 



. 0175 



.9998 



.0175 



16 





.2756 



.9613 



.2867 



31 





.5150 



.8572 



.6009 



1 30 



.0262 



.9997 



.0262 



16 



30 



.2840 



.9588 



.2962 



31 



30 



.5225 



.8526 



.6128 



2 



.0349 



.9994 



.0349 



17 





.2924 



.9563 



.3057 



32 





.5299 



.8480 



.6249 



2 30 



.0436 



.9990 



.0437 



17 



30 



.3007 



.9537 



.3153 



32 



30 



.5373 



.8434 



.6371 



3 



.0523 



.9986 



.0524 



18 





.3090 



.9511 



.3249 



33 





.5446 



.8387 



.6494 



3 30 



.0610 



.9981 



.0612 



18 



30 



.3173 



.9483 



.3346 



1 33 



30 



.5519 



.8339 



.6619 



4 



.0898 



.9976 



.0699 



19 





.3256 



.9455 



.3443 



34 





.5592 



.8290 



.6745 



4 30 



.0785 



.9969 



.0787 



19 



30 



.3338 



.9426 



.3541 



34 



30 



.5664 



.8241 



.6873 



5 



.0872 



.9962 



.0875 



20 





.3420 



.9397 



.3640 



35 





.5736 



.8192 



.7002 



5 30 



.0958 



.9954 



.0963 



20 



30 



.3502 



.9367 



.3739 



35 



30 



.5807 



.8141 



.7133 



6 



.1045 



.9945 



.1051 



21 





.3584 



.9336 



.3839 



36 





.5878 



.8090 



.7265 



6 30 



.1132 



.9936 



.1139 



21 



30 



.3665 



.9304 



.3939 



36 



30 



.5948 



.8039 



.7400 



7 



.1219 



.9925 



.1228 



22 





.3746 



.9272 



.4040 



37 





.6018 



.7986 



.7536 



7 30 



. 1305 



.9914 



.1317 



22 



30 



.3827 



.9239 



.4142 



37 



30 



.6088 



.7934 



.7673 



8 



.1392 



.9903 



.1405 



23 





.3907 



.9205 



.4245 



38 





.6157 



.7880 



.7813 



8 30 



.1478 



.9890 



.1495 



23 



30 



.3987 



.9171 



.4348 



38 



30 



.6225 



.7826 



.7954 



9 



. 1564 



.9877 



.1584 



24 





.4067 



.9135 



.4452 



39 





.6293 



.7771 



.8098 



9 30 



. 1650 



.9863 



.1673 



24 



30 



.4147 



.9100 



.4557 



39 



30 



.6361 



.7716 



.8243 



10 



. 1736 



.9848 



.1763 



25 





.4226 



.9063 



.4663 



40 





.6428 



.7660 



.8391 



10 30 



. 1822 



.9833 



.1853 



25 



30 



.4305 



.9026 



.4770 



40 



30 



.6494 



.7604 



.8541 



11 



.1908 



.9816 



.1944 



26 





.4384 



.8988 



.4877 



41 





.6561 



.7547 



.8693 



11 30 



.1994 



.9799 



.2035 



26 



30 



.4462 



.8949 



.4986 



41 



30 



.6626 



.7490 



.8847 



12 



.2079 



.9781 



.2126 



27 





.4540 



.8910 



.5095 



42 





.6691 



.7431 



.9004 



12 30 



.2164 



.9763 



.2217 



27 



30 



.4617 



.8870 



.5206 



42 



30 



.6756 



.7373 



.9163 



13 



.2250 



.9744 



.2309 



28 





.4695 



.8829 



.5317 



43 





.6820 



.7314 



.9325 



13 30 



.2334 



.9724 



.2401 



28 



30 



.4772 



.8788 



.5430 



43 



30 



.6884 



.7254 



.9490 



14 



.2419 



.9703 



.2493 



29 





.4848 



.8746 



.5543 



44 





.6947 



.7193 



.9657 



14 30 



. 2504 



.9681 



.2586 



29 



30 



.4924 



.8704 



.5658 



44 



30 



.7009 



.7133 



.9827 



15 



.2588 



.9659 



.2679 



30 





.5000 



.8660 



.5774 



45 





.7071 



.7071 



1. 0000 



