v. w j ra ' ' 



Depending upon th- i-lai;\-- \- 

 tin* pole, and the center of the circle* equation [39] ha* 



1 SJ.IM i.il t"..rms : 



then 0, " 

 equation [89] becomes 



ft 2 f>j/> cwi + />!* i" 1 = 



(/9) If the poll* is on tin* < inlc, thru />, - r, and jna- 



tion [89] becomes 



p _ . ^ - ^j) = ; 



(7) If tin- j r axis a d 



i h.-n f>! = r and ^ 0, and equation [89] becomes 



If the center is at the pole, then p, = and equation 

 P~- 



99. Equation of a circle referred to oblique axes. l.--t the 

 axes OX and OY 1x3 inelim-d at an angle >; let C = (A, 4:) 

 be the center of the circle, r 

 its radius, and />=(>, j/) 



Draw tin- / / N 



ordi nates A/jC and AT/', connect 

 1 draw CI/L paral- 



lei to tin- y-axis ; tln-n 



hence r - (x - A) -- (y - k? + J .^M. 



-*) 1 4-(y-*) 1 -h2(x-A)(y-*)cos-r-0;.. 



uliirli is tin- ri|uati<'M ,.f the given circle. 



