On the first day of the new academic year, rita, a class teacher,found that there were 10 new students in her class of 20 students.then she asked the new students to introduce themselves and shake hands with each other. find out the no. of handshakes. rita then asked to shake hands with the old students.find out the total no.of handshakes. is there a pattern in the no. of handshakes?can you generalize this?

the number of handshakes in first case is 45
a very good questin
the pattern for the first question is ∑(n-1)


The number of handshakes are 45 in the first case
1 5 1