Explicație pas cu pas:
[tex] \sin^{2} (17) + \cos^{2} (17) = 1[/tex]
[tex]\sin^{2} (23) + \sin^{2} (67) \\ =\sin^{2} (23) + \cos^{2} (90 - 67) \\ = \sin^{2} (23) + \cos^{2} (23) = 1[/tex]
[tex]\sin^{2} (56) - \cos^{2} (34) \\ = \cos^{2} (90 - 56) - \cos^{2} (34) \\ = \cos^{2} (34) + \cos^{2} (34)= 0[/tex]
[tex] \tan(47) \times \cot(47) = \frac{ \sin(47) }{\cos(47) } \times \frac{ \cos(47) }{ \sin(47) } = 1[/tex]
[tex] \frac{ \tan(53) }{ \cot(37) } =\frac{ \tan(53) }{ \cot(90 - 53) } =\frac{ \tan(53) }{ \tan(53) } = 1[/tex]
[tex] \cot(42) \times \tan(90 - 48) = \cot(42) \times \tan(42) = \frac{ \cos(42) }{\sin(42) } \times \frac{ \sin(42) }{ \cos(42) } = 1[/tex]
