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# P6 vector qustion.. 'Hence' calculate volume ? watch

1. hiya, it's vector again giving me trouble.

this question is from Heinemann P6 textbook Ex4B Q10.

---------------->question begins!!

The points A, B, C, D have position vectors

a = (2i + j)
b = (3i - j + k)
c = (-2i - k)
d = (2i - j +3k) respectively.

(a) Find AB X BC and BD X DC.
(b) Hence find
(i) the area of ABC
(ii) the volume of the tetrahedron ABCD.

yeah.. didn't have a clue for (b)(ii).
i mean, i can do it by usual formula, but the question specifically asked for 'hence'. Is there a way to do it using AB X BC and BD X DC?

Any suggestion would be grateful
2. It's still an application of the formula. The "hence" part is there because you already have the bxc part, I believe.
3. so i see..

haha.. the question scared me! thanks anyway

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