1.

Find radius of the circle \( 2 x^{2}+2 y^{2}+p x+p y \).

Answer»

The given equation of circle is

2x2 + 2y2 + px + py = 0

⇒ x2 + y2 + p/2 x + p/2 y = 0 (Dividing both sides by 2)

⇒ (x2 + p/2 x + p2/16) + (y2 + p/2 y + p2/16) - p2/16 - p2/16 = 0

(Adding and subtracting p2/16 in L.H.S)

⇒ (x + p/4)2 + (y + p/4)2 = 2p2/16 = p2/8

By comparing (x - h)2 + (y - k)2 = r2, we get

h = \(\frac{-p}4\) and k = \(\frac{-p}4\)

and r2 = p2/8

⇒ r = r/22

Hence, radius of the circle is r = p/22



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