Bonjour, Si quelqu'un peut m'aider je vous remercie d'avance. Voici les questions:a) sin(30°-x)=cos(.... Pergunta de ideia deIkram18

Ikram18 @Ikram18

April 2019 1 37 Report

Bonjour, Si quelqu'un peut m'aider je vous remercie d'avance. Voici les questions:

a) sin(30°-x)=cos(2x-60°) b) 2cos3x+√3=0

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Angel16

Coucou,

Il faut déjà avoir en tete que sin(alpha - beta) = sin(alpha)cos(beta) - cos(alpha)sin(beta)
ET cos(alpha - beta) = cos(alpha)cos(beta) + sin(alpha)sin(beta)

a)sin(30°-x)=cos(2x-60°)

sin(30)cosx - cos(30)sinx = cos2x cos(60) + sin2x sin(60)

d'après le cercle trigonométrique cos(30)= V3/2, et sin(30) = 1/2 ainsi que cos(60) =1/2 et sin(60)=V3/2

1/2cosx -V3/2sinx = 1/2cos2x+ V3/2sin2x

1/2cosx - cosx (car 1/2 *2=1)= V3/2sinx+ V3sinx (car V3/2*2=V3)

(1/2 -1)cosx = (V3/2+V3) sinx

tanx = sinx/cosx = (V3/2+V3)/ (1/2 -1)= je te laisse terminer

puis tu fais x = Arctan(ce que tu trouves)=...

et tu obtiens la valeur en degré

b)je te l'envoie en privée

Voilà ;)

quelqu'un pourrait corriger mon devoir? please My friend's name is youssra. She is eighteen like me. We met in a school homework. She was looking someone who could help in Spanish, I speak spanish so i helped she. Since that day, we became friends. We have a lot of common, she doesn't like to eat fish and me not. We don't like mathematics. We love Spanish. We have the same style. and this summer, we was going together in London. I had know for a year. I see she three times a week. Please help me, that is for tomorrow

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