7 7 r = __ 4 5 r = __ 2 3 r = __ 2 49 2 2 ___ [(x 5) + (y 2) = 16 ] C( 4 ; 8) r=4 [(x + 4)2 + (y 8)2 = 16] 26 C(3 ; 3) r = 3 2 [(x 1)2 + (y 6)2 = 16] 27 3 1 C(__ ; __) 2 4 r = 2 2 2 _1_ [(x + 4) + (y 2) = 4] 28 C(2 2 ; 0) r = 2 29 C(0 ; 4) r=2 [x2 + (y 4)2 = 4] 30 C(0 ; 3) r=1 [x2 + (y 3 )2 = 1] 13 C(1 ; 1) r=1 [(x 1)2 + (y + 1)2 = 1] 22 C(5 ; 2) 14 C(2 ; 3) r=4 [(x 2)2 + (y 3)2 = 16] 23 C(1 ; 4) 15 C(1 ; 2) r=5 [(x 1)2 + (y 2)2 = 25] 24 C(2 ; 6) 16 C( 1 ; 3) r=3 [(x + 1)2 + (y 3)2 = 9] 25 17 C(2 ; 4) r=6 [(x 2)2 + (y 4)2 = 36] 18 C(1 ; 6) r=4 19 1 C( 4 ; __) 2 r=2 20 C( 2 ; 2) r = 2 2 [(x 2 )2 + (y 2 )2 = 8] 21 1 C( 3 ; __) 5 r=2 __ __ __ ESERCIZI Circonferenze __ __ 1 2 2 __ [(x + 3) + (y 5) = 4] __ __ 25 2 2 ___ [(x 1) + (y + 4) = 4 ] 2 2 _9_ [(x 2) + (y + 6) = 4 ] __ __ __ [(x 3)2 + (y + 3)2 = 18] 3 2 1 2 __ __ [(x 2) + (y 4) = 2] __ [(x 2 2 )2 + y2 = 2] __ esercizio svolto C(3 ; 1) r=5 L equazione della circonferenza di centro C(x0 ; y0) e raggio r è: (x x0)2 + (y y0)2 = r2. Con x0 = 3, y0 = 1, r = 5 otteniamo: (x 3)2 + (y + 1)2 = 25 Sviluppando i quadrati ricaviamo la forma polinomiale: x2 6x + 9 + y2 + 2y + 1 25 = 0 da cui svolgendo i calcoli otteniamo l equazione generale richiesta: x2 + y2 6x + 2y 15 = 0 1 C(1 ; __) 2 1 37 C __ ; 4 (2 ) 31 C(2 ; 7) r=3 [x2 + y2 4x + 14y + 44 = 0] 32 5 C(0 ; __) 2 r=2 [4x2 + 4y2 20y + 9 = 0] 33 C( 1 ; 1) r = 3 [x2 + y2 + 2x + 2y 1 = 0] 38 C( 1 ; 3) 34 __ 1 C( 1 ; __) r = 2 [16x2 + 16y2 + 32x 8y 15 = 0] 4 39 C(1 ; 3) 35 C(3 ; 1) 40 C( 2 ; 0) 1 3 C(__ ; __) 2 4 1 42 C __ ; 2 (3 ) 41 43 C(4 ; 6) 44 C( 2 ; 3) __ r=2 [x2 + y2 6x + 2y + 6 = 0] r=5 1 r = __ 2 3 r = __ 4 36 __ __ r=3 [4x2 + 4y2 8x 4y 31 = 0] r=4 [4x2 + 4y2 4x 32y + 1 = 0] r=2 [x2 + y2 + 2x 6y + 6 = 0] r=4 [x2 + y2 2x 2 3 y 12 = 0] r=5 [x2 + y2 2 2 x 23 = 0] __ __ [16x2 + 16y2 16x 24y 387 = 0] [36x2 + 36y2 24x 144y + 139 = 0] [16x2 + 16y2 128x 192y 823 = 0] __ r = 5 [x2 + y2 + 4x 6y + 8 = 0] 377