S\u1ed1 pi (\u03c0) l\u00e0 g\u00ec?<\/p>\n\n\n\n
S\u1ed1 pi l\u00e0 t\u1ec9 s\u1ed1 gi\u1eefa chu vi v\u00f2ng tr\u00f2n v\u1edbi \u0111\u01b0\u1eddng k\u00ednh. Cho d\u00f9 v\u00f2ng tr\u00f2n c\u00f3 to \u0111\u1ebfn m\u1ea5y th\u00ec t\u1ec9 s\u1ed1 n\u00e0y v\u1eabn nh\u01b0 v\u1eady, n\u00ean \u0111\u00f3 l\u00e0 m\u1ed9t h\u1eb1ng s\u1ed1. Trong to\u00e1n h\u1ecdc ng\u01b0\u1eddi ta g\u1ecdi l\u00e0 s\u1ed1 pi. \u03c0 l\u00e0 ch\u1eef c\u00e1i \u0111\u1ea7u ti\u00ean trong t\u1eeb chu vi c\u1ee7a ti\u1ebfng Hy L\u1ea1p.<\/p>\n\n\n\n
Trong cu\u1ed9c s\u1ed1ng h\u00e0ng ng\u00e0y, trong ho\u1ea1t \u0111\u1ed9ng s\u1ea3n xu\u1ea5t, s\u1ed1 \u03c0 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng r\u1ea5t r\u1ed9ng r\u00e3i v\u00e0 c\u0169ng l\u00e0 m\u1ed9t s\u1ed1 r\u1ea5t \u0111\u1eb7c bi\u1ec7t.<\/p>\n\n\n\n
Nh\u01b0ng gi\u00e1 tr\u1ecb c\u1ee7a s\u1ed1 \u03c0 b\u1eb1ng bao nhi\u00eau?<\/p>\n\n\n\n
T\u1eeb x\u01b0a \u0111\u1ebfn nay, kh\u00f4ng bi\u1ebft c\u00f3 bao nhi\u00eau nh\u00e0 to\u00e1n h\u1ecdc \u0111\u00e3 lao t\u00e2m kh\u1ed5 t\u1ee9 \u0111\u1ec3 t\u00ednh s\u1ed1 \u03c0 v\u00e0 t\u00ednh gi\u00e1 tr\u1ecb s\u1ed1 \u03c0 ng\u00e0y c\u00e0ng ch\u00ednh x\u00e1c h\u01a1n. N\u00f3i chung \u0111\u1ec3 t\u00ednh s\u1ed1 \u03c0 ng\u01b0\u1eddi ta l\u1ee3i d\u1ee5ng chu vi c\u1ee7a c\u00e1c \u0111a gi\u00e1c \u0111\u1ec1u n\u1ed9i ti\u1ebfp ho\u1eb7c ngo\u1ea1i ti\u1ebfp v\u00f2ng tr\u00f2n \u0111\u1ec3 thay th\u1ebf g\u1ea7n \u0111\u00fang chu vi c\u1ee7a v\u00f2ng tr\u00f2n. Ban \u0111\u1ea7u ng\u01b0\u1eddi ta cho r\u1eb1ng c\u00f3 th\u1ec3 t\u00ednh \u0111\u01b0\u1ee3c \u0111\u1ebfn c\u00f9ng to\u00e0n b\u1ed9 gi\u00e1 tr\u1ecb c\u1ee7a s\u1ed1 \u03c0. Th\u1ebf nh\u01b0ng t\u00ednh \u0111i t\u00ednh l\u1ea1i, c\u00e0ng t\u00ednh l\u1ea1i c\u00e0ng th\u1ea5y kh\u00f4ng th\u1ec3 t\u00ednh \u0111\u01b0\u1ee3c \u0111\u1ebfn c\u00f9ng. M\u00e3i \u0111\u1ebfn th\u1ebf k\u1ec9 th\u1ee9 XIX, nh\u00e0 to\u00e1n h\u1ecdc \u0110\u1ee9c Lindeman (1882) m\u1edbi ch\u1ee9ng minh \u0111\u01b0\u1ee3c s\u1ed1 \u03c0 l\u00e0 s\u1ed1 v\u00f4 t\u1ec9 (s\u1ed1 th\u1eadp ph\u00e2n v\u00f4 h\u1ea1n, kh\u00f4ng tu\u1ea7n ho\u00e0n) theo m\u1ed9t quy t\u1eafc nh\u1ea5t \u0111\u1ecbnh c\u00f3 th\u1ec3 t\u00ednh \u0111\u1ebfn v\u00f4 h\u1ea1n, kh\u00f4ng gi\u1ed1ng nh\u01b0 ph\u00e2n s\u1ed1 nh\u01b0 1\/3, tuy l\u00e0 \u201cv\u00f4 t\u1eadn\u201d nh\u01b0ng l\u1ea1i \u0111\u01a1n gi\u1ea3n. D\u01b0\u1edbi \u0111\u00e2y ch\u00fang ta s\u1ebd xem x\u00e9t c\u1ed1ng hi\u1ebfn c\u1ee7a c\u00e1c nh\u00e0 to\u00e1n h\u1ecdc v\u1ec1 c\u00e1ch t\u00ednh s\u1ed1 \u03c0.<\/p>\n\n\n\n
T\u1eeb xa x\u01b0a \u1edf Trung Qu\u1ed1c \u0111\u00e3 c\u00f3 c\u00e2u \u201cchu vi ba, \u0111\u01b0\u1eddng k\u00ednh m\u1ed9t\u201d (t\u1ee9c \u03c0 = 3). Ngay t\u1eeb n\u0103m 100 tr\u01b0\u1edbc C\u00f4ng nguy\u00ean (v\u00e0o th\u1eddi T\u00e2y H\u00e1n) trong s\u00e1ch \u201cChu b\u00ec to\u00e1n kinh\u201d \u0111\u00e3 c\u00f3 n\u00f3i v\u1ec1 v\u1ea5n \u0111\u1ec1 n\u00e0y. \u0110\u1ebfn th\u1eddi \u0110\u00f4ng H\u00e1n, nh\u00e0 to\u00e1n h\u1ecdc, thi\u00ean v\u0103n h\u1ecdc Tr\u01b0\u01a1ng Ho\u00e0nh (n\u0103m 78- 139) \u0111\u00e3 d\u00f9ng m\u1ed9t s\u1ed1 k\u00ec di\u1ec7u l\u00e0 c\u0103n b\u1eadc hai c\u1ee7a s\u1ed1 10 l\u00e0m s\u1ed1 \u03c0 (\u221a10 = 3,16).<\/p>\n\n\n\n
\u0110\u00e2y l\u00e0 con s\u1ed1 r\u1ea5t d\u1ec5 nh\u1edb. V\u00e0o th\u1eddi Ngu\u1ef5 – T\u1ea5n, nh\u00e0 to\u00e1n h\u1ecdc L\u01b0u Huy, v\u00e0o n\u0103m 263 trong t\u00e1c ph\u1ea9m \u201cS\u00e1ch to\u00e1n ch\u00edn ch\u01b0\u01a1ng\u201d \u0111\u00e3 ch\u1ec9 ra r\u1eb1ng \u201cChu vi ba, \u0111\u01b0\u1eddng k\u00ednh m\u1ed9t\u201d ch\u1ec9 l\u00e0 t\u1ec9 s\u1ed1 gi\u1eefa chu vi c\u1ee7a h\u00ecnh l\u1ee5c gi\u00e1c \u0111\u1ec1u n\u1ed9i ti\u1ebfp trong v\u00f2ng tr\u00f2n v\u1edbi \u0111\u01b0\u1eddng k\u00ednh c\u1ee7a v\u00f2ng tr\u00f2n, do \u0111\u00f3 ch\u1ec9 c\u00f3 th\u1ec3 d\u00f9ng \u0111\u1ec3 t\u00ednh di\u1ec7n t\u00edch c\u1ee7a h\u00ecnh \u0111a gi\u00e1c \u0111\u1ec1u 12 c\u1ea1nh n\u1ed9i ti\u1ebfp trong v\u00f2ng tr\u00f2n. \u0110\u1ec3 t\u00ednh \u0111\u01b0\u1ee3c di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n ch\u00ednh x\u00e1c h\u01a1n, \u00f4ng \u0111\u00e3 s\u00e1ng t\u1ea1o ph\u01b0\u01a1ng ph\u00e1p c\u1eaft nh\u1ecf v\u00f2ng tr\u00f2n. D\u00f9ng ph\u01b0\u01a1ng ph\u00e1p chia nh\u1ecf v\u00f2ng tr\u00f2n \u00f4ng \u0111\u00e3 t\u00ednh di\u1ec7n t\u00edch c\u1ee7a h\u00ecnh 192 c\u1ea1nh \u0111\u1ec1u n\u1ed9i ti\u1ebfp trong v\u00f2ng tr\u00f2n v\u00e0 t\u00ecm \u0111\u01b0\u1ee3c s\u1ed1 \u03c0 = 157\/30 = 3,14. V\u1ec1 sau L\u01b0u Huy l\u1ea1i ti\u1ebfp t\u1ee5c t\u00ednh di\u1ec7n t\u00edch c\u1ee7a h\u00ecnh \u0111a gi\u00e1c 3072 c\u1ea1nh \u0111\u1ec1u n\u1ed9i ti\u1ebfp trong v\u00f2ng tr\u00f2n v\u00e0 t\u00ednh \u0111\u01b0\u1ee3c s\u1ed1 \u03c0 \u0111\u1ebfn \u0111\u1ed9 ch\u00ednh x\u00e1c \u03c0 = 3927\/1250 = 3,1416. L\u01b0u Huy \u0111\u00e3 d\u00f9ng ph\u01b0\u01a1ng ph\u00e1p t\u00ednh di\u1ec7n t\u00edch c\u1ee7a c\u00e1c \u0111a gi\u00e1c \u0111\u1ec1u n\u1ed9i ti\u1ebfp trong v\u00f2ng tr\u00f2n \u0111\u1ec3 t\u00ecm gi\u00e1 tr\u1ecb g\u1ea7n \u0111\u00fang di\u1ec7n t\u00edch c\u1ee7a h\u00ecnh tr\u00f2n ch\u00ednh l\u00e0 quan ni\u1ec7m gi\u1edbi h\u1ea1n, m\u1ed9t s\u00e1ng t\u1ea1o r\u1ea5t l\u1edbn trong to\u00e1n h\u1ecdc.<\/p>\n\n\n\n
Th\u00e0nh t\u00edch t\u00ednh s\u1ed1 \u03c0 r\u1ef1c r\u1ee1 h\u01a1n l\u00e0 c\u1ee7a T\u1ed5 Xung Chi th\u1eddi Nam – B\u1eafc Tri\u1ec1u (n\u0103m 429- 500). \u00d4ng \u0111\u00e3 t\u00ednh \u0111\u01b0\u1ee3c s\u1ed1 \u03c0 l\u00e0 s\u1ed1 \u1edf gi\u1eefa hai s\u1ed1 3,1415925 v\u00e0 3,1415927, kh\u00f4ng h\u1ec1 c\u00f3 ch\u1eef s\u1ed1 n\u00e0o sai. \u0110\u00e2y ch\u00ednh l\u00e0 s\u1ed1 \u03c0 v\u1edbi b\u1ea3y s\u1ed1 l\u1ebb \u0111\u1ea7u ti\u00ean tr\u00ean th\u1ebf gi\u1edbi. Th\u00e0nh qu\u1ea3 n\u00e0y c\u1ee7a T\u1ed5 Xung Chi \u0111\u01b0\u1ee3c ghi trong s\u00e1ch \u201cXuy\u1ebft thu\u1eadt\u201d. V\u1ec1 sau T\u1ed5 Xung Chi c\u00f2n \u0111\u01b0a ra hai gi\u00e1 tr\u1ecb s\u1ed1 \u03c0 kh\u00e1c vi\u1ebft d\u01b0\u1edbi d\u1ea1ng ph\u00e2n s\u1ed1 \u0111\u00f3 l\u00e0 \u201c\u01b0\u1edbc s\u1ed1\u201d \u03c0 = 22\/7 = 3,14 v\u00e0 \u201cm\u1eadt s\u1ed1\u201d \u03c0 = 355\/113 = 3,1415929. \u01b0\u1edbc s\u1ed1 ch\u00ednh b\u1eb1ng s\u1ed1 \u03c0 do Archim\u00e8de, nh\u00e0 to\u00e1n h\u1ecdc Hy L\u1ea1p \u0111\u00e3 t\u00ednh ra tr\u01b0\u1edbc \u0111\u00f3. Th\u1ebf nh\u01b0ng m\u1eadt s\u1ed1 th\u00ec m\u00e3i \u0111\u1ebfn th\u1ebf k\u1ec9 XVI m\u1edbi \u0111\u01b0\u1ee3c xu\u1ea5t hi\u1ec7n \u1edf Ch\u00e2u \u00c2u do nh\u00e0 to\u00e1n h\u1ecdc Ph\u00e1p Otto (1550 – 1605) v\u00e0 nh\u00e0 to\u00e1n h\u1ecdc H\u00e0 Lan Antoniss (1527 – 1607) t\u00ednh ra. So v\u1edbi T\u1ed5 Xung Chi th\u00ec mu\u1ed9n h\u01a1n \u0111\u1ebfn h\u01a1n 1000 n\u0103m. Hi\u1ec7n nay c\u00f3 m\u1ed9t d\u00e3y n\u00fai \u1edf ph\u00eda sau M\u1eb7t Tr\u0103ng \u0111\u01b0\u1ee3c \u0111\u1eb7t t\u00ean l\u00e0 T\u1ed5 Xung Chi \u0111\u1ec3 t\u1ecf l\u00f2ng ng\u01b0\u1ee1ng m\u1ed9 c\u1ee7a th\u1ebf gi\u1edbi \u0111\u1ed1i v\u1edbi \u00f4ng.<\/p>\n\n\n\n
T\u1eeb sau th\u1ebf k\u1ec9 XV, khoa h\u1ecdc k\u0129 thu\u1eadt \u1edf Ch\u00e2u \u00c2u ph\u00e1t tri\u1ec3n h\u1ebft s\u1ee9c m\u1ea1nh m\u1ebd. C\u00e1c nh\u00e0 nghi\u00ean c\u1ee9u v\u1ec1 c\u1ea7u ph\u01b0\u01a1ng (t\u00ecm m\u1ed9t h\u00ecnh vu\u00f4ng c\u00f3 di\u1ec7n t\u00edch t\u01b0\u01a1ng \u0111\u01b0\u01a1ng v\u1edbi h\u00ecnh tr\u00f2n) ng\u00e0y c\u00e0ng nhi\u1ec1u, nh\u1edd v\u1eady gi\u00e1 tr\u1ecb s\u1ed1 \u03c0 ng\u00e0y c\u00e0ng \u0111\u01b0\u1ee3c t\u00ednh ch\u00ednh x\u00e1c h\u01a1n. Ng\u01b0\u1eddi ta cho r\u1eb1ng s\u1ed1 \u03c0 c\u00e0ng t\u00ednh \u0111\u01b0\u1ee3c v\u1edbi nhi\u1ec1u s\u1ed1 l\u1ebb ch\u1eebng n\u00e0o th\u00ec c\u00e0ng qu\u00ed. Ph\u00e1t minh n\u00e0y \u0111\u00e3 \u0111\u01b0\u1ee3c nh\u00e0 to\u00e1n h\u1ecdc \u0110\u1ee9c Rudolph (1540 – 1610) t\u00ednh ra. Qua vi\u1ec7c t\u00ednh chu vi c\u1ee7a h\u00ecnh 262 c\u1ea1nh \u0111\u1ec1u n\u1ed9i ti\u1ebfp, \u00f4ng \u0111\u00e3 t\u00ednh ra s\u1ed1 \u03c0 v\u1edbi 35 s\u1ed1 l\u1ebb, qua ki\u1ec3m tra c\u1ee7a nh\u00e0 to\u00e1n h\u1ecdc kh\u00f4ng c\u00f3 ch\u1eef s\u1ed1 n\u00e0o b\u1ecb sai. \u00d4ng th\u1ea5y r\u1ea5t t\u1ef1 h\u00e0o v\u00e0 \u0111\u1ec3 l\u1ea1i di ch\u00fac kh\u1eafc 35 ch\u1eef s\u1ed1 n\u00e0y l\u00ean bia m\u1ed9 c\u1ee7a \u00f4ng. V\u00ec v\u1eady cho \u0111\u1ebfn nay c\u00f3 ng\u01b0\u1eddi \u0110\u1ee9c v\u1eabn g\u1ecdi s\u1ed1 \u03c0 l\u00e0 \u201cs\u1ed1 Rudolph\u201d.<\/p>\n\n\n\n
T\u1eeb sau th\u1ebf k\u1ec9 XVII, v\u1edbi s\u1ef1 ph\u00e1t tri\u1ec3n v\u00e0 ho\u00e0n thi\u1ec7n c\u1ee7a ph\u00e9p t\u00ednh vi ph\u00e2n, t\u00edch ph\u00e2n, c\u00e1ch t\u00ednh s\u1ed1 \u03c0 c\u00f3 s\u1ef1 thay \u0111\u1ed5i v\u1ec1 b\u1ea3n ch\u1ea5t. T\u1eeb vi\u1ec7c t\u00ednh s\u1ed1 \u03c0 d\u1ef1a v\u00e0o t\u00ednh \u0111\u1ed9 d\u00e0i c\u1ee7a c\u00e1c h\u00ecnh nhi\u1ec1u c\u1ea1nh \u0111\u1ec3 chuy\u1ec3n sang vi\u1ec7c t\u00ednh t\u1ed5ng c\u00e1c chu\u1ed7i s\u1ed1 gi\u1ea3m d\u1ea7n. \u0110\u00e2y l\u00e0 ph\u01b0\u01a1ng ph\u00e1p t\u00ednh to\u00e1n d\u1ef1a v\u00e0o khai tri\u1ec3n theo c\u1ea5p s\u1ed1 c\u1ee7a c\u00e1c h\u00e0m l\u01b0\u1ee3ng gi\u00e1c ng\u01b0\u1ee3c.<\/p>\n\n\n\n
V\u00ed d\u1ee5: H\u00e0m arctan (|x| \u2264 1)<\/p>\n\n\n\n
V\u00e0 ch\u00fa r\u1eb1ng arctan 1 = \u03c0\/4 . Trong c\u00f4ng th\u1ee9c tr\u00ean n\u1ebfu x = 1 ta s\u1ebd thu \u0111\u01b0\u1ee3c c\u00f4ng th\u1ee9c Leibnitz<\/p>\n\n\n\n
\u0110\u00e2y l\u00e0 c\u00e1ch d\u00f9ng chu\u1ed7i s\u1ed1 v\u00f4 h\u1ea1n \u0111\u1ec3 t\u00ednh s\u1ed1 \u03c0 \u0111\u01a1n gi\u1ea3n nh\u1ea5t, nh\u01b0ng r\u1ea5t kh\u00f3 t\u00ednh to\u00e1n v\u00ec c\u00e1c s\u1ed1 h\u1ea1ng gi\u1ea3m d\u1ea7n v\u1edbi t\u1ed1c \u0111\u1ed9 r\u1ea5t nh\u1ecf, cho d\u00f9 d\u00f9ng s\u1ed1 c\u00e1c s\u1ed1 h\u1ea1ng c\u1ee7a chu\u1ed7i \u0111\u1ebfn r\u1ea5t l\u1edbn. Do v\u1eady ng\u01b0\u1eddi ta \u0111\u00e3 kh\u00f4ng ng\u1eebng \u0111i s\u00e2u t\u00ecm c\u00e1c h\u00e0m s\u1ed1 l\u01b0\u1ee3ng gi\u00e1c ng\u01b0\u1ee3c c\u00f3 th\u1ec3 t\u00ecm \u0111\u01b0\u1ee3c c\u00f4ng th\u1ee9c t\u00ednh s\u1ed1 \u03c0 h\u1eefu hi\u1ec7u nh\u1ea5t. V\u00ed d\u1ee5 c\u00e1c c\u00f4ng th\u1ee9c.<\/p>\n\n\n\n
Nh\u1edd c\u00e1c th\u00e0nh qu\u1ea3 c\u1ee7a ph\u00e9p t\u00ednh vi ph\u00e2n, t\u00edch ph\u00e2n, vi\u1ec7c t\u00ednh s\u1ed1 \u03c0 \u0111\u00e3 b\u01b0\u1edbc v\u00e0o th\u1eddi k\u00ec m\u1edbi. S\u1ed1 c\u00e1c con s\u1ed1 l\u1ebb sau d\u1ea5u ph\u1ea3y \u0111\u01b0\u1ee3c t\u0103ng r\u1ea5t nhanh: V\u00e0o n\u0103m 1706 \u0111\u1ea1t \u0111\u1ebfn 100 ch\u1eef s\u1ed1 (Martin), n\u0103m 1794 \u0111\u1ebfn 140 ch\u1eef s\u1ed1 (Weija), n\u0103m 1824 \u0111\u1ebfn 152 ch\u1eef s\u1ed1 (Rutherford), n\u0103m 1844 \u0111\u1ea1t \u0111\u1ebfn 205 ch\u1eef s\u1ed1 (Daize), n\u0103m 1853 \u0111\u1ebfn 400 ch\u1eef s\u1ed1 (Rutherford), n\u0103m 1855 \u0111\u00e3 \u0111\u1ebfn 500 ch\u1eef s\u1ed1 (Leibauder). K\u1ec9 l\u1ee5c v\u1ec1 s\u1ed1 \u03c0 \u1edf cu\u1ed1i th\u1ebf k\u1ec9 XIX do m\u1ed9t nh\u00e0 to\u00e1n h\u1ecdc Anh W. Schanks c\u00f3 707 ch\u1eef s\u1ed1 th\u1eadp ph\u00e2n, t\u00ednh v\u00e0 c\u00f4ng b\u1ed1 v\u00e0o n\u0103m 1874. \u0110i\u1ec1u c\u1ea7n ch\u00fa \u00fd l\u00e0 s\u1ed1 \u03c0 do \u00f4ng t\u00ednh \u0111\u01b0\u1ee3c ch\u1ec9 ch\u00ednh x\u00e1c \u0111\u1ebfn ch\u1eef s\u1ed1 528, c\u00f2n c\u00e1c ch\u1eef s\u1ed1 ph\u00eda sau th\u00ec sai.<\/p>\n\n\n\n
\u0110\u1ebfn n\u0103m 1947 s\u1ed1 \u03c0 \u0111\u01b0\u1ee3c t\u00ednh \u0111\u1ebfn 808 ch\u1eef s\u1ed1 l\u1ebb (Fuchlin). \u0110\u00f3 l\u00e0 k\u1ec9 l\u1ee5c cao nh\u1ea5t \u0111\u01b0\u1ee3c ghi l\u1ea1i tr\u01b0\u1edbc khi m\u00e1y t\u00ednh \u0111i\u1ec7n t\u1eed ra \u0111\u1eddi.<\/p>\n\n\n\n
T\u1eeb khi xu\u1ea5t hi\u1ec7n m\u00e1y t\u00ednh \u0111i\u1ec7n t\u1eed, vi\u1ec7c d\u00f9ng m\u00e1y t\u00ednh \u0111i\u1ec7n t\u1eed \u0111\u00e3 l\u00e0m cho s\u1ed1 ch\u1eef s\u1ed1 l\u1ebb th\u1eadp ph\u00e2n c\u1ee7a s\u1ed1 \u03c0 t\u0103ng nhanh v\u1edbi t\u1ed1c \u0111\u1ed9 kinh ng\u01b0\u1eddi. Ngay t\u1eeb n\u0103m 1949 \u0111\u00e3 c\u00f3 ng\u01b0\u1eddi trong v\u00f2ng m\u1ed9t ng\u00e0y \u0111\u00eam \u0111\u00e3 t\u00ednh \u0111\u01b0\u1ee3c s\u1ed1 \u03c0 v\u1edbi 2048 ch\u1eef s\u1ed1 l\u1ebb (trong \u0111\u00f3 c\u00f3 2037 ch\u1eef s\u1ed1 ch\u00ednh x\u00e1c); \u0111\u1ebfn n\u0103m 1967, s\u1ed1 \u03c0 \u0111\u00e3 c\u00f3 50 v\u1ea1n ch\u1eef s\u1ed1, n\u0103m 1988 \u0111\u1ea1t \u0111\u1ebfn 200 tri\u1ec7u ch\u1eef s\u1ed1, n\u0103m 1989 \u0111\u1ebfn 1 t\u1ec9 ch\u1eef s\u1ed1.<\/p>\n\n\n\n
<\/p>\n\n\n\n\n\n\n","protected":false},"excerpt":{"rendered":"
S\u1ed1 pi (\u03c0) l\u00e0 g\u00ec? S\u1ed1 pi l\u00e0 t\u1ec9 s\u1ed1 gi\u1eefa chu vi v\u00f2ng tr\u00f2n v\u1edbi \u0111\u01b0\u1eddng k\u00ednh. Cho d\u00f9 v\u00f2ng tr\u00f2n c\u00f3 to \u0111\u1ebfn m\u1ea5y th\u00ec t\u1ec9 s\u1ed1 n\u00e0y v\u1eabn nh\u01b0 v\u1eady, n\u00ean \u0111\u00f3 l\u00e0 m\u1ed9t h\u1eb1ng s\u1ed1. Trong to\u00e1n h\u1ecdc ng\u01b0\u1eddi ta g\u1ecdi l\u00e0 s\u1ed1 pi. \u03c0 l\u00e0 ch\u1eef c\u00e1i \u0111\u1ea7u ti\u00ean trong […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_disable_autopaging":false},"categories":[15,9],"tags":[],"class_list":["post-7644","post","type-post","status-publish","format-standard","hentry","category-hoi-dap-khoa-hoc","category-toan-hoc"],"_links":{"self":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7644","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/comments?post=7644"}],"version-history":[{"count":0,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7644\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/media?parent=7644"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/categories?post=7644"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/tags?post=7644"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}