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Résolvez l'équation \(\sin 2x = \cos x\) .
\( S=\left\{\dfrac{\pi}{2},\, \dfrac{\pi}{6}\right\} \)
\( S=\left\{\dfrac{\pi}{2}+2k\pi,\, \dfrac{\pi}{6}+2k\dfrac{\pi}{3};\, k\in\mathbb{Z}\right\} \)
\(S=\left\{\dfrac{\pi}{2}+2k\pi,\, \dfrac{\pi}{6}+2k\pi;\, k\in\mathbb{Z}\right\} \)
\( S=\left\{-\dfrac{\pi}{2}+2k\pi,\, \dfrac{\pi}{6}+2k\dfrac{\pi}{3};\, k\in\mathbb{Z}\right\} \)
Résolvez l'équation \(4\cos^4 x-5\cos^2 x+1 =0\) .
\( S=\left\{\dfrac{1}{4}+2k\pi,\, 1+2k\pi;\, k\in\mathbb{Z}\right\}\)
\( S=\left\{-\dfrac{\pi}{3}+2k\pi,\, \dfrac{\pi}{3}+2k\pi,\, 2k\pi;\, k\in\mathbb{Z}\right\} \)
\( S=\left\{-\dfrac{2\pi}{3}+2k\pi,\, -\dfrac{\pi}{3}+2k\pi,\, \dfrac{\pi}{3}+2k\pi,\, \dfrac{2\pi}{3}+2k\pi,\, \pi+2k\pi,\, 2k\pi;\, k\in\mathbb{Z}\right\} \)
\(S=\emptyset \)
Résolvez l'équation \(tg\, 2x-tg\, 3x=0\) .
\(S=\left\{0,\, -\pi\right\} \)
\( S=\left\{2k\pi;\, k\in\mathbb{Z}\right\} \)
\( S=\left\{k\pi;\, k\in\mathbb{Z}\right\} \)
\( S=\left\{\dfrac{\pi}{4}+k\dfrac{\pi}{2},\, \dfrac{\pi}{6}+k\dfrac{\pi}{3};\, k\in\mathbb{Z}\right\} \)
A l'aide des formules, calculez \(\sin\left(\dfrac{\pi}{12}\right) \).
\(\dfrac{\sqrt{2}+\sqrt{6}}{4} \)
\(\dfrac{\sqrt{2}-\sqrt{6}}{4} \)
\( \dfrac{\sqrt{6}-\sqrt{2}}{4} \)
\( \dfrac{\sqrt{3}-\sqrt{2}}{2} \)
Résolvez l'équation \(2\cos^2 x-3\cos x+1 =0\) .
\( S=\left\{1+2k\pi,\, \dfrac{1}{2}+2k\pi;\, k\in\mathbb{Z}\right\} \)
\( S=\left\{\dfrac{\pi}{3}+2k\pi,\, 2k\pi;\, k\in\mathbb{Z}\right\} \)
\( S=\left\{\dfrac{\pi}{3}+2k\pi,\, -\dfrac{\pi}{3}+2k\pi,\, 2k\pi;\, k\in\mathbb{Z}\right\} \)
Résolvez l'équation \(3\sin^2{\alpha}-\cos^2{\alpha}=2\) sachant que \(\alpha\in [\dfrac{\pi}{2},\dfrac{3\pi}{2}]\) .
\( S=\left\{\dfrac{2\pi}{3}, \dfrac{4\pi}{3}\right\} \)
\( S=\left\{\dfrac{5\pi}{6}, \dfrac{7\pi}{6}\right\} \)
\( S=\left\{\dfrac{\pi}{3}, \dfrac{2\pi}{3}, \dfrac{4\pi}{3}, \dfrac{5\pi}{3}\right\} \)
\( S=\left\{\dfrac{2\pi}{3}\right\}\)
Si \(\alpha\) est un angle du troisième quadrant tel que \(\sin\alpha\cdot\cos\alpha=\dfrac{1}{2}\), calculez \(\sin\alpha+\cos\alpha\) .
\( \sqrt{2} \)
\( -\sqrt{2} \)
\( -1 \)
impossible
A l'aide des formules, calculez \(\cos\left(\dfrac{\pi}{12}\right)\) .
\( \dfrac{1-\sqrt{2}}{2} \)
\( \dfrac{\sqrt{2}+\sqrt{6}}{4} \)
\( \dfrac{\sqrt{2}-\sqrt{6}}{4} \)
Résolvez l'équation \(\cos{x}+\cos{2x}=0 \).
\( S=\left\{-1,\, \dfrac{1}{2}\right\} \)
\( S=\left\{\dfrac{\pi}{3},\, \dfrac{5\pi}{3},\, \pi\right\} \)
\( S=\left\{\dfrac{\pi}{3}+2k\pi,\, \dfrac{5\pi}{3}+2k\pi,\, \pi+2k\pi;\, k\in\mathbb{Z}\right\} \)
\(S=\left\{\dfrac{\pi}{3}+2k\pi,\, \pi+2k\pi;\, k\in\mathbb{Z}\right\} \)
Déterminez la hauteur d'un chêne sachant que l'angle d'élévation de sa cîme passe de 30 degrés à 75 degrés lorsque l'observateur se rapproche de 30 mètres du pieds de l'arbre.
\(30\) mètres
\( \dfrac{30}{\sqrt{2}} \) mètres
\( \dfrac{1}{60}(\sqrt{3}+1) \) mètres
\( \dfrac{15}{2}(\sqrt{3}+1)\) mètres
