Question Number 30505 by abdo imad last updated on 22/Feb/18
$${find}\:\:{A}=\sum_{{k}=\mathrm{0}} ^{{n}} \:{ch}\left({a}+{kb}\right)\:{and}\:{B}=\sum_{{k}=\mathrm{0}} ^{{n}} \:{sh}\left({a}+{kb}\right). \\ $$
find-A-k-0-n-ch-a-kb-and-B-k-0-n-sh-a-kb-