I need help with B!
1 answer:
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Answer:
See Explanation Below
Step-by-step explanation:
The question is incomplete (because the figure to calculate the perimeter is missing).
However from the comment attached to your question, I understand that the figure looks like a plus sign.
The perimeter of a plane shape is calculated by adding the length of each side of the shape.
Take for instance;
A square of length 5cm.
We know that a square has 4 equal sides; meaning that the length of the other sides are also 5cm
So, the perimeter of the square will be calculated as 5cm + 5cm + 5cm + 5cm = 20cm
Similarly, the perimeter of a triangle whose sides are 4ft, 3ft and 5ft will be calculated by adding up the length of the three sides.
Perimeter of the triangle = 4ft + 3ft + 5ft
Perimeter = 12ft.
Having explained how the perimeter of a plane shape is calculated; take for example, the attachment below.
(The sides are measured in centimetres)
The plus sign has 12 sides; Its perimeter is calculated by adding up the length of the 12 sides.
Perimeter = 3 + 7 + 7 + 5 + 5 + 5 + 5 + 2 + 2 + 4 + 4 + 3
Perimeter = 52cm
Using the determinant method, the cross product is
so the answer is B.
Or you can apply the properties of the cross product. By distributivity, we have
(3i + 8j - 6k) x (-4i - 2j - 3k)
= -12(i x i) - 32(j x i) + 24(k x i) - 6(i x j) - 16(j x j) + 12(k x j) - 9(i x k) - 24(j x k) + 18(k x k)
Now recall that
- (i x i) = (j x j) = (k x k) = 0 (the zero vector)
- (i x j) = k
- (j x k) = i
- (k x i) = j
- (a x b) = -(b x a) for any two vectors a and b
Putting these rules together, we get
(3i + 8j - 6k) x (-4i - 2j - 3k)
= -32(-k) + 24j - 6k + 12(-i) - 9(-j) - 24i
= (-12 - 24)i + (24 + 9)j + (32 - 6)k
= -36i + 33j + 26k