Does anyone can help me how to find [tex]r * sin \theta * d\phi[/tex] (please see attached image)?(adsbygoogle = window.adsbygoogle || []).push({});

Here some other that I can solve:

FIRST

[tex]d\theta = L / r[/tex]

so

[tex]L = r * d\theta[/tex]

SECOND

[tex]sin \theta = P / r[/tex]

so

[tex]P = r * sin \theta[/tex]

THIRD

[tex]d\phi = B / r[/tex]

so

[tex]B = r * d\phi[/tex]

FOURTH

The pink-hatched region is a regular rectangle with lengthand widthL.W

So the area of this rectangle denoted bydis:S

[tex]dS = width * length

= (r * sin \theta * d\phi) (r * d\theta)

= r^2 * sin \theta * d[tex]\theta * d\phi[/tex]

Also, how to obtain [tex]d\omega = dS / r^2[/tex]?

Thanks in advance

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# Simple geometrical problem

Can you offer guidance or do you also need help?

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