Vector in the plane of a and b, perpendicular to a given vector, with a given projection on a: find its length
The same question, asked 2 times: 2021 Paper 8*, 2021 Paper 24. Every wording below, oldest first.
Try each one first, then open its answer.
Question 1
2021 Paper 8
88
Let x be a vector in the plane containing vectors a=2i−j+k and b=i+2j−k. If the vector x is perpendicular to (3i+2j−k) and its projection on a is 2176, then the value of ∣x∣2 is equal to
Question 2
2021 Paper 24
88
Let a=2i−j+2k and b=i+2j−k. Let a vector v be in the plane containing a and b. If v is perpendicular to the vector 3i+2j−k and its projection on a is 19 units, then ∣2v∣2 is equal to
