Analytical ChemistryHard
Question
Let Tn be the number of all possible triangles formed by joining vertices of an n-sided regular polygon. If Tn+1 - Tn = 10, then the value of n is :
Options
A.7
B.5
C.10
D.8
Solution
Tn = nC3 ⇒ n+1C3 - nC3 = 10
(n + 1) n (n - 1) - n(n - 1) (n - 2) = 60
n(n - 1) = 20
n = 5
(n + 1) n (n - 1) - n(n - 1) (n - 2) = 60
n(n - 1) = 20
n = 5
Create a free account to view solution
View Solution FreeMore Analytical Chemistry Questions
Which onr amongst the following pairs of ions cannot be separated by H2S in dilute HCL ?...Which of the following statement is not correct ?...H2S does not produce metallic sulphide with :...A mixture upon adding conc. H2SO4 gives deep red fumes. It may contain the anions pair :...Black precipitate of copper sulphide dissolves in :...