CHAP. IV.] 



MELOID AND APIOID. 



99 



For take any point C, mDC + w CB = thread, and m DC + mAC 

 = m AD ; therefore take away m DC, and n CB ~ m AC = thread 

 ~ m AD = constant quantity. As m > n, A is called the greater and B 

 the less focus. 



Proposition 2 is the same as proposition 2 of the Oval. 



PKOPOSITION 3 THEOREM. 



If a circle be described with a focus for a center, and the constant 

 difference divided by the power of that focus for a radius, the distance 

 of any point in the curve from the other focus is to the distance from 

 the circle as the power of the central focus is to the power of the other. 



