++ = ++ oooo ooooo 3sin15 25' 4cos12 12'sin42 20' cos36 15' B; 2cos15 25' 3cos65 13'.sin15 12' cos31 33'.sin18 20' 143,08.xvôùi), 1xxxx x2 1x 1 (:) 1x x (1C = + - - + += 625 86 1010.1376 = ) 4R abc S;c)b)(pa)(pp(pS = = 0,1,2, nvôùi a 11aa a1,a n n 2 n 1no = -++ == + 1n a + 2 5 x 2 15 y:)(d 2 3 x 2 13 y:)(d 1 - - =+ + = 2 (2)34017)1y(y4017)x(x (1)040300562009x2610x13x 22 23 =+++- = 3 1 y 2008x = = . nvôùi a 11aa a1,a n n 2 n 1no = -++ == + 1n a + 2 5 x 2 15 y:)(d 2 3 x 2 13 y:)(d 1 - - =+ + = 2 (2)34017)1y(y4017)x(x (1)040300562009x2610x13x 22 23 =+++- = 3 1 y 2008x = =