Áp dụng t/c tổng 3 góc trong 1 tam giác
=> \(\widehat{C}=180-60-36=84\)
Áp dụng định lí sin:
\(\dfrac{AB}{sin84}=\dfrac{BC}{sin60}=\dfrac{AC}{sin36}\)
\(\Rightarrow\left\{{}\begin{matrix}BC=\dfrac{sin60.AB}{sin84}\\AC=\dfrac{sin36.AB}{sin84}\end{matrix}\right.\)
\(AC+BC=\dfrac{AB\left(sin60+sin36\right)}{sin84}=\dfrac{2\left(sin60+sin36\right)}{sin84}\simeq2,9\)