Question

$\tan {48}^o\tan {23}^o\tan {42}^o\tan {67}^o\ne 1$
Enter $1$ for true and $0$ for false

Answer 1

$\tan {48}^o\tan {23}^o\tan {42}^o\tan {67}^o$
$=\tan {48}^{\circ }.\tan {23}^{\circ }.\tan ({90}^{\circ }-{48}^{\circ }).\tan ({90}^{\circ }-{67}^{\circ })=\tan {48}^{\circ }.\tan {23}^{\circ }.\cot {48}^{\circ }.\cot {23}^{\circ }=1$