. sui.ii>. 

 ro x l stands for 



v. stands for 



will !* easily seen by drawinc a 6gure so as to make 

 the planes bounding the si fee parallel to that of (or, y), and 

 dgea of the strip para .e axis o: 



I*-t it bv ri-<juircd to find the centre of gravity of 

 the solid bounded by the planes : = fix, s = yx, and the < 

 der y*-2ox-x l . We shall have 



rr 



5il^Lzl 



where y, is put for 



Now !*<& -(?-) 



I** Jdxdy 



:ore 



ffcffi ' 



I I ' xdxdy 

 J J -f i 





fore 



(See Integral Calculus, Ex. 5 to Chap, in.) 

 Similarly we may find 



