... I = lim 0,5 0 ,25 0 ,25 0 ,25 0 ,25 1,0 0,5 0 ,25 0 ,25 1,0 0 ,25 0 ,25 0 ,25 cos2x-1 −2sin x. (2 + − x ) sin x + lim = lim = lim ÷ 2 x (2 + − x ) = x → 2- 4-x x → (2 − − x ) (2 + − x ) x →0 ... SAD có: 2 AH AS AD 2a a 2a + Đoạn vuông góc chung : Qua H kẻ HP//CD//AB cắt SC P Qua P kẻ PQ//AH cắt AB Q Suy : PQ đoạn vuông góc chung AB SC cos2x-1 − sin x + + lim x →0 2- 4-x x →0 2- 4-x I ... x + = lim x→0 x→0 2- 4-x 1+ + lim ( (1 − sin x − 1). (2 + − x ) sin x + + sin x + (2 − + x) sin x = lim ÷ x→0 3x 1+ Vậy I= - 0 ,25 ) ( ( ) ( −3). (2 + − x ) 1,0 ) ( sin...