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العربية

sin^2(2x)=2sin^2(x)cos^2(x)

Solution

sin^{2} (2 x) = 2 sin^{2} (x) cos^{2} (x)

x = \frac{π}{2} + 2 πn, x = \frac{3 π}{2} + 2 πn, x = 2 πn, x = π + 2 πn

Degrés

x = 9 0^{\circ} + 36 0^{\circ} n, x = 27 0^{\circ} + 36 0^{\circ} n, x = 0^{\circ} + 36 0^{\circ} n, x = 18 0^{\circ} + 36 0^{\circ} n

étapes des solutions

sin^{2} (2 x) = 2 sin^{2} (x) cos^{2} (x)

Soustraire

2 sin^{2} (x) cos^{2} (x)

des deux côtés

sin^{2} (2 x) - 2 sin^{2} (x) cos^{2} (x) = 0

Récrire en utilisant des identités trigonométriques

sin^{2} (2 x) - 2 cos^{2} (x) sin^{2} (x)

Utiliser l'identité d'angle double:

sin (2 x) = 2 sin (x) cos (x)

= (2 sin (x) cos (x))^{2} - 2 cos^{2} (x) sin^{2} (x)

Simplifier

(2 sin (x) cos (x))^{2} - 2 cos^{2} (x) sin^{2} (x) : 2 sin^{2} (x) cos^{2} (x)

(2 sin (x) cos (x))^{2} - 2 cos^{2} (x) sin^{2} (x)

Appliquer la règle de l'exposant:

(a \cdot b)^{n} = a^{n} b^{n}

= 2^{2} sin^{2} (x) cos^{2} (x) - 2 cos^{2} (x) sin^{2} (x)

2^{2} = 4

= 4 sin^{2} (x) cos^{2} (x) - 2 cos^{2} (x) sin^{2} (x)

Additionner les éléments similaires :

4 sin^{2} (x) cos^{2} (x) - 2 cos^{2} (x) sin^{2} (x) = 2 sin^{2} (x) cos^{2} (x)

= 2 sin^{2} (x) cos^{2} (x)

= 2 sin^{2} (x) cos^{2} (x)

2 cos^{2} (x) sin^{2} (x) = 0

En solutionnant chaque partie séparément

cos^{2} (x) = 0 or sin^{2} (x) = 0

cos^{2} (x) = 0 : x = \frac{π}{2} + 2 πn, x = \frac{3 π}{2} + 2 πn

cos^{2} (x) = 0

Appliquer la règle

x^{n} = 0 \Rightarrow x = 0

cos (x) = 0

Solutions générales pour

cos (x) = 0

Tableau de périodicité

cos (x)

avec un cycle

2 πn

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

x = \frac{π}{2} + 2 πn, x = \frac{3 π}{2} + 2 πn

x = \frac{π}{2} + 2 πn, x = \frac{3 π}{2} + 2 πn

sin^{2} (x) = 0 : x = 2 πn, x = π + 2 πn

sin^{2} (x) = 0

Appliquer la règle

x^{n} = 0 \Rightarrow x = 0

sin (x) = 0

Solutions générales pour

sin (x) = 0

Tableau de périodicité

sin (x)

avec un cycle

2 πn

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

x = 0 + 2 πn, x = π + 2 πn

x = 0 + 2 πn, x = π + 2 πn

Résoudre

x = 0 + 2 πn : x = 2 πn

x = 0 + 2 πn

0 + 2 πn = 2 πn

x = 2 πn

x = 2 πn, x = π + 2 πn

Combiner toutes les solutions

x = \frac{π}{2} + 2 πn, x = \frac{3 π}{2} + 2 πn, x = 2 πn, x = π + 2 πn

\frac{sin ( 7 0 ^{\circ} )}{25} = \frac{sin ( c )}{26}

1.25 sin (3 0^{\circ}) = 1.5 sin (x)

3 sin (3 x) + 3 cos (3 x) = 0

tan (θ) = - \frac{4}{5}, \frac{π}{2} < θ < π

cos (2 x) = sin (x), 0 \leq x < 2 π