Question

Sa se arate ca:
a)$\frac{cos12°+ \sqrt{3} sin12°}{cos3°-sin3°} = \sqrt{2}$
b)$\frac{cos5°+sin25°}{cos25°-sin5°} = \sqrt{3}$
c)$sin^{4} \frac{ \pi }{8} + sin^{4} \frac{3 \pi }{8} + sin^{4} \frac{5 \pi }{8} + sin^{4} \frac{7 \pi }{8} = \frac{3}{2}$
d)$cos^{4} \frac{ \pi }{8} + cos^{4} \frac{3 \pi }{8} + cos^{4} \frac{5 \pi }{8} + cos^{4} \frac{7 \pi }{8} = \frac{3}{2}$
e)$sin20°*sin40°*sin60°*sin80°= \frac{3}{16}$
Acel A cu caciulita arata ca acolo sunt grade (cos12grade,sin12grade...)si el nu se afla in enunt.
Multumesc mult!

Answer 1

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