Question

If a^2 = b and b^2 = a, where a not equal to b, then the value of a + b is :​

Answer 1

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12th

Maths

Three Dimensional Geometry

Angles between Two lines in 3D Space

If | A × B | = √(3) A.B , ...

PHYSICS

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Asked on October 15, 2019 by

Tamana Sindhu

If ∣A×B∣=

3

A.B, then the value of ∣A+B∣ is :

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VIDEO EXPLANATION

ANSWER

We know that,

A×B=ABsinθ

Also, A.B=ABcosθ

Given : ∣A×B∣=

3

A.B

Using ∣A×B∣=∣A∣∣B∣sinθ

We get ∣A×B∣=ABsinθ

A.B=∣A∣∣B∣cosθ

∴ ABsinθ=

3

ABcosθ

tanθ=

3

⟹θ=60

o

Now (A+B)

2

=A

2

+B

2

+2A.B

=A

2

+B

2

+2ABcosθ

=A

2

+B

2

+2AB×

2

1

=A

2

+B

2

+AB

or ∣A+B∣=(A

2

+B

2

+AB)

1/2