Sa se arate ca:
a)[tex] \frac{cos12+ \sqrt{3}sin12 }{cos3-sin3}= \sqrt{2} [/tex]
b)[tex] \frac{cos5+sin25}{cos25-sin5} = \sqrt{3} [/tex]
c)[tex] sin^{4} \frac{ \pi }{8} + sin^{4} \frac{ 3\pi }{8} + sin^{4} \frac{5 \pi }{8} + sin^{4} \frac{ 7\pi }{8} = \frac{3}{2} [/tex]
d)[tex] cos^{4} \frac{ \pi }{8} + cos^{4} \frac{ 3\pi }{8} + cos^{4} \frac{5 \pi }{8} + cos^{4} \frac{ 7\pi }{8} = \frac{3}{2} [/tex]
e)sin20*sin40*sin60*sin80=[tex] \frac{3}{16} [/tex]