Chapter 9: Q. 21 (page 627)

find (a) v × w, (b) w × v, (c) w × w, and
(d) v × v
v = i - j - k
w = 4i - 3k

Short Answer

Expert verified

v ×w= 3i -j+4k

w ×v= -3i+j -4k

w ×w=0

v ×v=0

Step by step solution

Step 1.Given information

v = i - j - k

w = 4i - 3k

Step 2. v× w

For two vectors

v=a₁i+b₁j+c₁k

w=a₂i+b₂j+c₂k

cross product v× w is written as

$v \times w = |\begin{matrix} i & j & k \\ a_{1} & b_{1} & c_{1} \\ a_{2} & b_{2} & c_{2} \end{matrix}| = i |\begin{matrix} b_{1} & c_{1} \\ b_{2} & c_{2} \end{matrix}| - j |\begin{matrix} a_{1} & c_{1} \\ a_{2} & c_{2} \end{matrix}| + k |\begin{matrix} a_{1} & b_{1} \\ a_{2} & b_{2} \end{matrix}|$

v = i - j - k

w = 4i - 3k

$v \times w = |\begin{matrix} i & j & k \\ 1 & - 1 & - 1 \\ 4 & 0 & - 3 \end{matrix}| = i |\begin{matrix} - 1 & - 1 \\ 0 & - 3 \end{matrix}| - j |\begin{matrix} 1 & - 1 \\ 4 & - 3 \end{matrix}| + k |\begin{matrix} 1 & - 1 \\ 4 & 0 \end{matrix}| = 3 i - j + 4 k$

Step 3. w × v

According to the algebraic properties of cross product

w × v = -(v × w)

so w × v= $-$ (3i-j+4k) = -3i+j-4k

Step 4. w× w and v× v

According to the algebraic properties of cross product the cross product of any vector with itself is the zero vector

(a ×a=0).

Hence w ×w=0 and v ×v=0

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find (a) v × w, (b) w × v, (c) w × w, and
(d) v × v
v = i - j - k
w = 4i - 3k

Short Answer

Step by step solution

Step 1.Given information

Step 2. v× w

Step 3. w × v

Step 4. w× w and v× v

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find (a) v × w, (b) w × v, (c) w × w, and(d) v × vv = i - j - kw = 4i - 3k

Short Answer

Step by step solution

Step 1.Given information

Step 2. v× w

Step 3. w × v

Step 4. w× w and v× v

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Math Textbooks

Probability and Statistics

Decision Maths

Geometry

Calculus

Theoretical and Mathematical Physics

Discrete Mathematics

Study anywhere. Anytime. Across all devices.

find (a) v × w, (b) w × v, (c) w × w, and
(d) v × v
v = i - j - k
w = 4i - 3k