Let a vertical tower AB of height 2h stands on a horizontal ground. Let from a point P on the ground a man can see up to height h of the tower with an angle of elevation 2α.When from P, he moves a distance d in the direction of \(\overrightarrow{AP}\).he can see the top B of the tower with an angle of elevation α. if \(d = \sqrt7\) h, then tan α is equal to
A vector \(\vec{a}\)is parallel to the line of intersection of the plane determined by the vectors\(\hat{i},\hat{i}+\hat{j} \)and the plane determined by the vectors \(\hat{i}−\hat{j},\hat{i}+\hat{k}\). The obtuse angle between \(\vec{a}\) and the vector \(\vec{b}=\hat{i}−2\hat{j}+2\hat{k}\)is
The letters of the work ‘MANKIND’ are written in all possible orders and arranged in serial order as in an English dictionary. Then the serial number of the word ‘MANKIND’ is ______.
If \(\sum\limits_{k=1}^{31}\) \((^{31}C_k) (^{31}C_{k-1})\) \(-\sum\limits_{k=1}^{30}\) \((^{30}C_k) (^{30}C_{k-1})\) \(= \frac{α (60!)} {(30!) (31!)}\)where \(α ∈ R\), then the value of 16α is equal to
If\((^{40}C_0) + (^{41}C_1) + (^{42}C_2) + ...... + (^{60}C_{20}) \frac{m}{n} ^{60}C_{20}\)m and n are coprime, then m + n is equal to _____.
The number of ways to distribute 30 identical candies among four children C1, C2, C3 and C4 so that C2 receives atleast 4 and atmost 7 candies, C3 receives atleast 2 and atmost 6 candies, is equal to: