AP EAMCET · Maths · Permutation Combination
\(T_m\) denotes the number of triangles that can be formed with the vertices of a regular polygon of \(m\) sides. If \(T_{m+1}-T_m=15\), then \(m\) is equal to
- A \(3\)
- B \(6\)
- C \(9\)
- D \(12\)
Answer & Solution
Correct Answer
(B) \(6\)
Step-by-step Solution
Detailed explanation
Given, \(T_m=\) Number of triangles formed with the vertices of a polygon of \(m\) sides. Also, \(T_{m+1}-T_m=15\) \(\Rightarrow \quad{ }^{m+1} C_3-{ }^m C_3=15\) ...(i) As we know, \({ }^n C_r+{ }^n C_{r+1}={ }^{n+1} C_{r+1}\)…
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