Disqus-comments, formatting

Here Is a small guide in Disqus-formatting, that I have ‘published’ several times on the old GSMArena.com blog (with tiny variation).

UPDATE: Should in 2019 finally be more or less obsolete for wide enough windows!

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Length of round (carpet) roll

Carpet

For some reason, surprisingly few know this extremely simple formula, please share it.

I have actually seen in a carpet store an employee unrolling the carpet to measure the length!!

[The formula is simple to prove too… r=kφ, L=∫r dφ=∫kφ dφ=½k(φ2²-φ1²)=½k(φ21)×(φ21)=½(r2+r1) ×n2π=(r2+r1) × nπ , q.e.d.]