Réponse : Bonjour,
Exercice 65
Pour tout [tex]x \in \mathcal{D}_{T}[/tex]:
[tex]\displaystyle \tan^{2}(x)=\left(\frac{\sin(x)}{\cos(x)}\right)^{2}=\frac{\sin^{2}(x)}{\cos^{2}(x)}=\frac{1-\cos^{2}(x)}{\cos^{2}(x)}=\frac{1}{\cos^{2}(x)}-\frac{\cos^{2}(x)}{\cos^{2}(x)}\\ \tan^{2}(x)=\frac{1}{\cos^{2}(x)}-1[/tex]
