Bài 30. Tìm tọa độ của các vectơ sau trong mặt phẳng tọa độ
\(\eqalign{
& \overrightarrow a = – \overrightarrow i \,;\,\,\,\,\,\,\,\,\,\,\,\,\overrightarrow b = 5\overrightarrow j \,\,;\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\overrightarrow c = 3\overrightarrow i – 4\overrightarrow j \,; \cr
& \overrightarrow d = {1 \over 2}(\overrightarrow j – \overrightarrow i \,\,\,)\,;\,\,\,\,\,\,\,\overrightarrow e = 0,15\overrightarrow i \,\, + 1,3\overrightarrow {j\,} \,;\,\,\,\,\,\,\,\,\overrightarrow f = \pi \overrightarrow i \,\, – (\cos {24^0})\overrightarrow {j\,} \,\,\,\,\,\,\,\,\,\,\, \cr} \)
\(\overrightarrow a = (x,\,y)\,\, \Rightarrow \,\overrightarrow a = x\overrightarrow i + y\overrightarrow j \)
Áp dụng điều trên, ta có
\(\eqalign{
& \overrightarrow a = ( – 1\,;\,0);\,\,\,\,\,\,\,\,\overrightarrow b = (0\,;\,5);\,\,\,\,\,\,\,\,\,\,\,\overrightarrow c = (3\,;\, – 4); \cr
& \overrightarrow d = ( – {1 \over 2}\,;\,{1 \over 2});\,\,\,\,\,\,\,\,\,\,\,\,\,\overrightarrow e = (0,15\,;\,1,3);\,\,\,\,\,\,\,\,\overrightarrow f = (\pi \,;\, – \cos {24^0}). \cr} \)