Question
( Rightarrow frac{2 sin A cos A cdot(1-cos A)}{(1-cos 2 A) cdot cos A} )
( Rightarrow frac{2 sin A(1-cos A)}{(1-cos 2 A)} )
( Rightarrow frac{2 sin A(1-cos A)}{xleft(1-left(2 cos ^{2} A-1right)right.} leq 1 )
( Rightarrow frac{2 sin A(1-cos A)}{2left(1-cos ^{2} Aright)}=frac{sin A}{1+cos A) cdot(1+cos A)}=frac{frac{2 tan A / 2}{left(+tan ^{2} A_{2}right.}}{1+frac{1-tan ^{2} A}{1+tan ^{2} A}} )

A 18. sin 2A 1- cos 2A 1-cos A cos A tan
Solution
