Question Number 7096 by Tawakalitu. last updated on 10/Aug/16
Commented by Rasheed Soomro last updated on 10/Aug/16
$${First}\:{vertex}\:{of}\:{a}\:{triangle}\:{can}\:{be} \\ $$$${chosen}\:{in}\:{n}\:{ways}\:{in}\:{a}\:{regular}\:{n}-{gon}. \\ $$$${The}\:{second}\:{vertex}\:{can}\:{be}\:{chosen}\:{in} \\ $$$${n}−\mathrm{1}\:{ways}.\:{The}\:{third}\:{vertex}\:{can}\:{be}\: \\ $$$${chosen}\:{in}\:{n}−\mathrm{2}\:{ways}. \\ $$$${So}\:{a}\:{triangle}\:{can}\:{be}\:{drawn}\:{in} \\ $$$${n}\left({n}−\mathrm{1}\right)\left({n}−\mathrm{2}\right)\:{ways}. \\ $$$${Or}\:\:{n}\left({n}−\mathrm{1}\right)\left({n}−\mathrm{2}\right)\:{triangles}\:{can}\:{be} \\ $$$${made}\:{from}\:{the}\:{vetices}\:{of}\:{n}-{gon}. \\ $$
Commented by Tawakalitu. last updated on 10/Aug/16
$${Thanks}\:{so}\:{much}\:..\:{i}\:{appereciate}. \\ $$
Commented by Tawakalitu. last updated on 10/Aug/16
$${The}\:{last}\:{number}\:\mathrm{3}\:{is}\:{the}\:{one}\:{i}\:{need}\:{now}\: \\ $$$${Thanks}\:{so}\:{much} \\ $$