Question

Спростіть вираз ctg a/sin a cos a -1

Answer 1

$\tt\displaystyle\frac{ctg(a)}{sin(a)\cdot cos(a)} - 1=\frac{\displaystyle\frac{cos(a)}{sin(a)}}{sin(a)\cdot cos(a)} - 1=\frac{cos(a)}{sin(a)\cdot sin(a)\cdot cos(a)}-1=\\\\\\=\frac{1 - sin^2(a)}{sin^2(a)}=\frac{cos^2(a)}{sin^2(a)}=ctg^2(a)$