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Clau161
a fost răspuns

sin^80°+sin^10° va rog

Răspuns :

KillingSlow
sin 10 = sin 90-10= cos 80
=> sin 80+cos 80 =1
(forumla fundam. a trigonometriei)

[tex]\it sinx+siny = 2sin\dfrac{x+y}{2}cos\dfrac{x-y}{2} \\\;\\ \\\;\\ sin80^o+sin10^o = 2sin\dfrac{80^o+10^o}{2}cos\dfrac{80^o-10^o}{2}=2sin45^ocos35^o= [/tex]

[tex]\it =2\cdot \dfrac{\sqrt2}{2} cos35^o =\sqrt2cos35^o[/tex]




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