The vector a = (1,2) B = (- 2, n) is known. The angle between a and B is 45 degrees
Cos = cos45 ° = √ 2 / 2; | cos = a · B / | a | ×| B | = (- 2 + 2n) / √ (1 + 4) √ (4 + n & # 178;) = √ 2 / 2; | 3N & # 178; - 16n-12 = 0; (3N + 2) (n-6) = 0; | n = - 2 / 3; or 6; | B = (- 2, - 2 / 3) or (- 2,6) if you don't understand this question, please remember to adopt it if you are satisfied, if you have other questions
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- 1. It is known that vector a = (1,2), vector b = (- 2, n) and the angle between vector a and B is 45 degrees (1) Finding the vector b (2) If the vector C and B are in the same direction, and C-A is perpendicular to a, find C
- 2. Given the vector a = (1,2), the vector b = (- 2, n), the angle between the vectors a and B is 45 °, find the vector B. if the vectors C and B are in the same direction, C-A ⊥ a, find C
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