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Let Tn be the number of all possible ...

Let `T_n` be the number of all possible triangles formed by joining vertices of an n-sided regular polygon. If `T_(n+1)-T_n=""10` , then the value of n is (1) 5 (2) 10 (3) 8 (4) 7

A

5

B

10

C

8

D

7

Text Solution

Verified by Experts

The correct Answer is:
A
`because T_(n+1)-T_(n)=10 implies.^(n+1)C_(3)-.^(n)C_(3)=10implies.^(n)C_(2)=.^(n)C_(3)-.^(n)C_(3)=10`
`implies.^(n)C_(2)=10=(20)/(2)=(5*4)/(1*2)=.^(5)C_(2)impliesn=5`
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