402 The Inverfe Method 
given being put ==v==sV, we fhall have by 
1 
; 2 n—t1 
reduction y= r X ———————_ and the 
s* x n—1 +2 
{pace defcended r —y = 7 X 
1 
en = eee go na—t1 ae 
sxe nl + | — 2 n1 
aE ee via 7 
pepe se | ee 
If nx==2, thenr—yo x r, which 
rary 
is general for all the conic fections. In the 
hyberbola, the tranfverfe axis = ae =, fup- 
pofe, to A (fee Cor. 2. Prop. 1.), therefore 
a dea a hence by fubftitution r — y = 
A 
At+r 
2A-+r mE 
In the parabol “ 
—y= 4. 
n the parabola, r ache orermiaat o, oP 
being inthis cafe = 2, 
5 r 
In the ellipfis, r — y = ay ae x #, the 
2 f 2% 
tranfverfe axis being Sle A. 
If 
