Question

show that tan 48 tan 23 tan 42 tan 67=1​

Answer 1

Step-by-step explanation:

$\tan(48) \tan(23) \tan(42) \tan(67) = 1 \\ \tan(99 - 42) \tan(90 - 67) \tan(42) \tan(67 )$

$\cot(42) \ \cot(67) \tan(42) \tan(67 )$

$\tan(42) \tan(67) \cot(42) \ \cot(67)$

$= 1$