Question Number 116177 by Khalmohmmad last updated on 01/Oct/20 Commented by Dwaipayan Shikari last updated on 01/Oct/20 $$\mathrm{tan}\left(\mathrm{x}−\frac{\pi}{\mathrm{2}}\right)\mathrm{tan}\left(\mathrm{x}+\frac{\pi}{\mathrm{2}}\right)=\mathrm{1} \\ $$$$\mathrm{tan}\left(\mathrm{x}−\frac{\pi}{\mathrm{2}}\right)=\mathrm{cot}\left(\mathrm{x}+\frac{\pi}{\mathrm{2}}\right) \\ $$$$\mathrm{tan}\left(\mathrm{x}−\frac{\pi}{\mathrm{2}}\right)=\mathrm{tan}\left(−\mathrm{x}\right) \\ $$$$\mathrm{x}−\frac{\pi}{\mathrm{2}}=\mathrm{k}\pi+\left(−\mathrm{x}\right) \\…
Question Number 115988 by bemath last updated on 30/Sep/20 Commented by mr W last updated on 01/Oct/20 $$\frac{\mathrm{7}!}{\mathrm{2}!\mathrm{2}!}−\mathrm{2}×\frac{\mathrm{6}!}{\mathrm{2}!}+\mathrm{5}!+\mathrm{2}×\left(\frac{\mathrm{5}!}{\mathrm{2}!}−\mathrm{4}!\right)=\mathrm{732} \\ $$ Commented by bemath last updated…
Question Number 115902 by bemath last updated on 29/Sep/20 $${The}\:{secret}\:{number}\:{is}\:{made}\:{from} \\ $$$${the}\:{numbers}\:\mathrm{1},\mathrm{2},\mathrm{2},\mathrm{3},\mathrm{3},\mathrm{4},\mathrm{5}.\: \\ $$$${Many}\:{secret}\:{numbers}\:{can}\:{be}\:{created} \\ $$$${if}\:{the}\:{same}\:{number}\:{is}\:{not}\:{adjacent} \\ $$$${except}\:{in}\:{the}\:{first}\:{two}\:{place}\:{is}\:\_ \\ $$$$\left({a}\right)\mathrm{1142}\:\:\:\:\left({b}\right)\:\mathrm{1212}\:\:\:\:\left({c}\right)\:\mathrm{1246} \\ $$$$\left({d}\right)\:\mathrm{1248}\:\:\:\left({e}\right)\:\mathrm{1250} \\ $$ Terms…
Question Number 50258 by rahul 19 last updated on 15/Dec/18 $${A}\:{delegation}\:{of}\:\mathrm{4}\:{students}\:{is}\:{to}\:{be} \\ $$$${selected}\:{from}\:{a}\:{total}\:{of}\:\mathrm{12}\:{students}. \\ $$$${In}\:{how}\:{many}\:{ways}\:{can}\:{the}\:{delegation} \\ $$$${be}\:{selected}\:{if}: \\ $$$$\left.\mathrm{1}\right)\:\mathrm{2}\:{particular}\:{students}\:{wish}\:{to}\:{be}\: \\ $$$${included}\:{together}\:{only}\:{in}\:{the}\:{delegation}? \\ $$$$\left.\mathrm{2}\right)\:\mathrm{2}\:{particular}\:{students}\:{refuse}\:{to}\:{be}\: \\ $$$${together}\:{and}\:\mathrm{2}\:{other}\:{particular}\:{students}…
Question Number 115769 by bemath last updated on 28/Sep/20 $${There}\:{are}\:\mathrm{3}\:{teachers}\:{and}\:\mathrm{6}\:{students} \\ $$$${who}\:{will}\:{sit}\:{on}\:{the}\:\mathrm{9}\:{available}\:{seats}.\:{many} \\ $$$${arrangements}\:{they}\:{sit}\:{if}\:{each}\: \\ $$$${teacher}\:{is}\:{flanked}\:{by}\:\mathrm{2}\:{students} \\ $$ Answered by mr W last updated on…
Question Number 181251 by cortano1 last updated on 23/Nov/22 Commented by cortano1 last updated on 23/Nov/22 $$\:\mathrm{A}\:\mathrm{photograph}\:\mathrm{is}\:\mathrm{to}\:\mathrm{be}\:\mathrm{taken}\:\mathrm{of}\:\mathrm{seven}\:\mathrm{girls}\: \\ $$$$\:\mathrm{standing}\:\mathrm{in}\:\mathrm{two}\:\mathrm{rows},\:\mathrm{with}\:\mathrm{one}\:\mathrm{row} \\ $$$$\mathrm{in}\:\mathrm{front}\:\mathrm{of}\:\mathrm{the}\:\mathrm{other}.\:\mathrm{The}\:\mathrm{tallest}\:\mathrm{girl}\: \\ $$$$\mathrm{must}\:\mathrm{be}\:\mathrm{in}\:\mathrm{the}\:\mathrm{midlle}\:\mathrm{of}\:\mathrm{the}\:\mathrm{row}\:\mathrm{of} \\ $$$$\mathrm{three}\:\mathrm{and}\:\mathrm{the}\:\mathrm{shortest}\:\mathrm{girl}\:\mathrm{must}\:\mathrm{be}…
Question Number 50008 by rahul 19 last updated on 13/Dec/18 $$\mathrm{5}−{digit}\:{number}\:{divisible}\:{by}\:\mathrm{3}\:{formed} \\ $$$${using}\:\mathrm{0},\mathrm{1},\mathrm{2},\mathrm{3},\mathrm{4},\mathrm{5}\:{without}\:{repetition}. \\ $$$${Total}\:{number}\:{of}\:{such}\:{no}.{s}\:{is}\:? \\ $$ Commented by rahul 19 last updated on 13/Dec/18…
Question Number 49982 by pieroo last updated on 12/Dec/18 $$\mathrm{If}\:\frac{\mathrm{n}_{\mathrm{P}_{\mathrm{r}} } }{\mathrm{n}_{\mathrm{C}_{\mathrm{r}} } }\:−\mathrm{1}=\mathrm{5},\:\mathrm{find}\:\mathrm{the}\:\mathrm{value}\:\mathrm{of}\:\mathrm{r} \\ $$ Answered by ajfour last updated on 13/Dec/18 $$\:^{{n}} {P}_{{r}}…
Question Number 115408 by mr W last updated on 25/Sep/20 $${how}\:{many}\:\mathrm{6}\:{digit}\:{numbers}\:{exist} \\ $$$${which}\:{are}\:{divisible}\:{by}\:\mathrm{11}\:{and}\:{have}\:{no} \\ $$$${repeating}\:{digits}? \\ $$ Answered by Olaf last updated on 26/Sep/20 $$\mathrm{N}\:=\:{a}_{\mathrm{5}}…
Question Number 115387 by bemath last updated on 25/Sep/20 Commented by bemath last updated on 25/Sep/20 $${p}=\:\frac{\:^{\mathrm{8}} {C}_{\mathrm{4}} ×!\mathrm{4}}{\mathrm{8}!}\:=\:\frac{\frac{\mathrm{8}!}{\mathrm{4}!.\mathrm{4}!}\:×\:\mathrm{9}}{\mathrm{8}!}\:=\:\frac{\mathrm{9}}{\mathrm{576}} \\ $$$$ \\ $$ Commented by…