Question

find the angle between a=4i+6j=-7k and b=3i +6j-7k. find a×b
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Answer 1

Answer:

Let the required angle be θ.

We know,

A.B = AB cosθ - - - - - - - - - - - - - - 1

=> θ = cos^-1 x [A.B/(AB)]

Now,

A.B= -8 - 30 - 21 = -59 By 1

A = (42 + 62 + 32)1/2 = 7.8

B = (22 + 52 +72)1/2 = 8.8

So. AB = 68.7 (approx)

Thus,

θ = cos^-1 x (-59/68.7) = 150

Explanation: