at a secret family meeting everyone shakes hand exactly once with every other person present. If there was a total of 28 handshakes, how big was the family?
QGP:
Which standard are you in? I need to know what level of Math to use
7th
Ahh Okay. Sure.
By the way, answer is 8 people
How???
Hey Wait. I asked Sidhanni for his/her standard. What is your standard @Siddhani?
who is Siddhani
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this is my own method. im giving it a try.
now let's take a polygon with 's' edges.
so now the number of hand shake is number of sides+diagonals.
now we should take the formula of no. of diagonals.
((n(n-3))/2)+n=n(n-3)+2n/2=28
now, by cross multiplication we get,
n(n-3)+2n=56
n2-3n+2n=56
n2-n=56
n(n-1)=56
n(n-1)=8*7
n(n-1)=8(8-1)
therefore,n=8
hope this helps you.
pls mark brainliest.
now let's take a polygon with 's' edges.
so now the number of hand shake is number of sides+diagonals.
now we should take the formula of no. of diagonals.
((n(n-3))/2)+n=n(n-3)+2n/2=28
now, by cross multiplication we get,
n(n-3)+2n=56
n2-3n+2n=56
n2-n=56
n(n-1)=56
n(n-1)=8*7
n(n-1)=8(8-1)
therefore,n=8
hope this helps you.
pls mark brainliest.
i did this using polygons.
directly you can take, number of persons n and no of handshakes by each person=n-1
but this method can't be used
if you don't divide it by two
which means you have to take n(n-1)/2=28
only then you will get the right answer
so i hope you understood the method of the polygons
it is to give you why is it n(n-1)/1 without confusion
pls mark brainliest if it was
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