Question

The resultant of two vectors of magnitude 3 units and 4 units is 1 unit. What is the value of their cross product

Answer 1

Step-by-step explanation:

R = 4^2 + 3^2 +2×3×4cos x

-1 = cosx

x = 180°

A×B = ABsin x

= 0

Answer 2

The value of their cross product=0

Step-by-step explanation:

Given:

R=1 unit

$\mid A\mid=3 units$

$\mid B\mid=4 units$

We know that resultant of two vectors

$R=\sqrt{\mid A\mid ^2+\mid B\mid^2-2\mid A\mid\mid B\mid cos\theta}$

Using the formula

$R=\sqrt{(3)^2+(4)^2-2(3)(4)cos\theta}$

$1=\sqrt{9+16-24cos\theta}$

Squaring on both sides

$1=25-24cos\theta$

$24cos\theta=25-1=24$

$cos\theta=\frac{24}{24}=1$

$cos\theta=cos0^{\circ}$

Using cos 0 degree=1

$\theta=0^{\circ}$

$\midA\times B\mid =\mid A\mid \mid B\mid sin\theta$

Using the formula

$\mid A\times B\mid=3\times 4sin0=0$

Because

$sin0^{\circ}=0$

$A\times B=0$

Hence, the value of their cross product=0

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https://brainly.in/question/15676642:Answered by Chintan