Grade 12th passMechanics

If a, b, c are three unit vectors and angle between a and b between b and c and between c and a is all equal to 60∘, then find ∣∣∣a→+2b→−3c→∣∣∣.

Aditya Pathak

8 Years agoGrade 12th pass

3 Answers

Arun

8 Years ago

Dear Aditya

I am not using vector sign. It is understood

Let

Z = |a + b +c|

On squaring both the side or dot product of self

Z² = a² + b² + c² + 2 a. b + 2 b. c + 2 c. a

Z² = 1 +1 +1 + 2 |a| |b| cos 60° + 2 |b| |c| cos 60° + 2 |c| |a| cos 60°

Z² = 3 + 1 + 1 + 1 = 6

Hence

Z = sqrt(6)

Deepak Kumar Shringi

Approved Tutor Answer8 Years ago

Arun

Approved Tutor Answer8 Years ago

Sorry,

I have taken a + b+ c while this is a + 2b +3c...

Sorry for that

But procedure will be same

Hope it helps

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If a, b, c are three unit vectors and angle between a and b between b and c and between c and a is all equal to 60∘, then find ∣∣∣a→+2b→−3c→∣∣∣.

Aditya Pathak

3 Answers

Arun

Deepak Kumar Shringi

Arun

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