Question Number 148881 by DELETED last updated on 01/Aug/21
Answered by Rasheed.Sindhi last updated on 01/Aug/21
$$\blacktriangle{ABC}=\sqrt{\mathrm{s}\left(\mathrm{s}−\mathrm{a}\right)\left(\mathrm{s}−\mathrm{b}\right)\left(\mathrm{s}−\mathrm{c}\right)} \\ $$$$\:\:\:\:\:\:\mathrm{s}=\frac{\mathrm{a}+\mathrm{b}+\mathrm{c}}{\mathrm{2}}=\frac{\mathrm{7}+\mathrm{6}+\mathrm{8}}{\mathrm{2}}=\mathrm{10}.\mathrm{5} \\ $$$$\blacktriangle{ABC}=\sqrt{\mathrm{10}.\mathrm{5}\left(\mathrm{10}.\mathrm{5}−\mathrm{6}\right)\left(\mathrm{10}.\mathrm{5}−\mathrm{8}\right)\left(\mathrm{10}.\mathrm{5}−\mathrm{7}\right)} \\ $$$$\:\:\:\:\:\:\:=\sqrt{\mathrm{10}.\mathrm{5}×\mathrm{4}.\mathrm{5}×\mathrm{2}.\mathrm{5}×\mathrm{3}.\mathrm{5}}\approx\mathrm{20}.\mathrm{33}\:\mathrm{cm}^{\mathrm{2}} \\ $$