Sa se verifice egalitatile:
a)sin4x+2sin2x=4sin2x*[tex] cos^{2} x[/tex];
b) [tex](7+cos4x)^{2}
[/tex]=32(1+[tex]sin^{8}x
[/tex]+[tex]cos^{8}x
[/tex]);
c)[tex] \frac{sin2 a}{1+cos 2a} * \frac{cosa}{1+cosa} =tg \frac{a}{2}
[/tex]
d)[tex] \frac{1-2tga *ctg2a}{1+2ctga*ctg2a} = tg^{2}a.
[/tex] Multumesc mult!