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8. If A = −5i + 6j − 3k and B = 3i + 4j + 2k, determine A.(A × B)

User SvenG
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1 Answer

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Final answer:

To find A.(A × B), you need to calculate A × B (A cross B) and then take the dot product of A with the result. The dot product is -66.

Step-by-step explanation:

To find A.(A × B), we first need to calculate A × B (A cross B) and then take the dot product of A with the result.

A × B = (-5i + 6j - 3k) × (3i + 4j + 2k)

= (-5 * 3) î × î + (-5 * 4) î × ĵ + (-5 * 2) î × k + (6 * 3) ĵ × î + (6 * 4) ĵ × ĵ + (6 * 2) ĵ × k + (-3 * 3) k × î + (-3 * 4) k × ĵ + (-3 * 2) k × k

= 0 +0 +0 + 18k - 24k + 0 + -9j + 0 + 6i

= 6i - 9j - 6k

A.(A × B) = (-5i + 6j - 3k) . (6i - 9j - 6k)

= (-5 * 6) + (6 * -9) + (-3 * -6)

= -30 -54 +18

= -66

User IQAndreas
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