Can I distribute cotangent here???
cot(Arccot 3 + Arccot 7 + Arccot 15 + Arccot 21)
Can you please show the solution???
nope you cannot distribute the cotangent here, you will need to use the double angle formula here (several times)
first note that $\displaystyle \cot ( A + B ) = \frac{\cot A \cot B - 1}{\cot A + \cot B}$
so your thing becomes
$\displaystyle \cot( accot 3 + acot 7 + acot 15 + acot 21) = \frac{\cot (accot 3 + acot 7) \cot (acot 15 + acot 21) - 1}{\cot (accot 3 + acot 7) + \cot (acot 15 + acot 21)}
$
can you finish this off ?
Bobak