Open xjzsq opened 6 years ago
http://www.xjdesyxx.top/2018/03/02/yzqx/
$S_{\Delta OAB}=\frac{ab\lvert C\rvert\sqrt{a^2A^2+b^2B^2-C^2}}{a^2A^2+b^2B^2}$
http://www.xjdesyxx.top/2018/03/02/yzqx/