Question Number 196625 by sniper237 last updated on 28/Aug/23
$${Let}\:\:{a}={BC}\:\:{b}={CA}\:\:{c}={AB} \\ $$$${ABC}\:\:{is}\:{rectangle}\:{iff}\:\:{tan}\left(\frac{\hat {{A}}}{\mathrm{2}}\right)=\frac{{a}}{{b}+{c}} \\ $$
Let-a-BC-b-CA-c-AB-ABC-is-rectangle-iff-tan-A-2-a-b-c-