Question

Подскажите чему равен tg²x/3 ?

Answer 1

$\boxed {\ 1+tg^2\alpha =\dfrac{1}{cos^2\alpha }\ }\ \ \ \ \ \boxed {\ tg\alpha =\dfrac{sin\alpha }{cos\alpha }\ }\\\\\\\\tg^2\dfrac{x}{3}=\dfrac{1}{cos^2\frac{x}{3}}-1\ \ \ ,\ \ \ \ tg^2\dfrac{x}{3}=\dfrac{sin^2\frac{x}{3}}{cos^2\frac{x}{3}}$