Bài 1:
$sinC=cosB=\dfrac{AB}{BC}=\dfrac{12}{20}=\dfrac{3}{5}$
$cosC=sinB=\dfrac{AC}{BC}=\dfrac{16}{20}=\dfrac{4}{5}$
$tanC=cotB=\dfrac{AB}{AC}=\dfrac{12}{16}=\dfrac{3}{4}$
$cotC=tanB=\dfrac{AC}{AB}=\dfrac{16}{12}=\dfrac{4}{3}$
Bài 2:
Chưa đủ dữ kiện để tìm x, y