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Tg(Π/12) are valoarea? Sa nu imi ziceti valoare 0,39 sau asa ceva... Vreau expresie plsss..

Răspuns :

Folosim formula tg(x / 2) = sin x / (1 + cos x)
Rezulta: tg(x) = sin(2x) / (1 + cos(2x))

Aplicam formula:
tg(π/12) = sin(2 * π/12) / (1 + cos(2 * π /12)) = sin(π/6) / (1 + cos(π/6)) =
=(1 / 2) / (1 + √3 / 2) = 1 / (2 + √3) = 2 - √3 ≈ 0,2679


[tex]\it tg\dfrac{\pi}{12} = tg(\dfrac{\pi}{3}-\dfrac{\pi}{4}) = \dfrac{tg\dfrac{\pi}{3}-tg\dfrac{\pi}{4}}{1+tg\dfrac{\pi}{3}tg\dfrac{\pi}{4}} =\dfrac{\sqrt3 -1}{1+\sqrt3\cdot1} =\dfrac{\sqrt3-1}{\sqrt3+1} = \\\;\\ \\\;\\ =\dfrac{(\sqrt3-1)^2}{3-1}=\dfrac{4-2\sqrt3}{2} =\dfrac{2(2-\sqrt3)}{2} = 2-\sqrt3[/tex]