the unit vector that makes an angle feta=2pi/3 with the positive x-axis , find the component form of the vector
the unit vector obtained by rotating the vector <0,1> 120 degree counterclockwise about the origin, find the component form of the vector
vector
2008-09-08 5:33 pm
回答 (1)
2008-09-08 6:09 pm
✔ 最佳答案
1.The unit vector is cos120 i + sin 120 j = -(1/2)i + (sqrt 3)/2 j.
2.
Originally, the vector is j. after rotating 120 counterclockwise, new angle is 210.
Therefore the new vector is cos 210 i + sin 210 j = - (1/2) i - (sqrt 3)/2 j.
2008-09-08 10:11:52 補充：
Correction: For Q2. the new vector should be -(sqrt 3)/2 i - (1/2) j. Sorry.
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https://hk.answers.yahoo.com/question/index?qid=20080908000051KK00367