Answers

The Brainliest Answer!
2015-05-03T03:49:44+05:30

This Is a Certified Answer

×
Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
A pair of lines represented by :
                    L1 : ax + by + c = 0  ,  slope = m1 = -a/b
                and  L2 = d x + e y + f = 0        slope  m2 = - d/e

 L1L2:     (a x + b y + c) (d x + e y + f) = 0

L1L2:   a d x² + b e y² + (b d + a e) x y + (a f + c d) x + (b f + c e) y + c f  = 0

So a pair of straight lines has a XY term.

    =  (ad/be) x² + y² + (d/e + a/b) x y + (af + cd)/be  x + (f/e + c/b) y + cf/ be = 0
   =  m1 m2 x² + y² - (m1 + m2) x y + ( af + cd)/be x +  (f/e + c/b) y  + cf/be = 0
in this form, the coefficient of x y is the sum of slopes of the lines.
=====================
a circles:

   generally  for a circle, the equation is :    (x - a)²  +  (y - b)² = r²

  This does not contain a term in XY.

2 5 2