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Aleen1997
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Cum calculez cos de pi/8, respectiv cos de pi/8?

Răspuns :

Lennox
Cos π/4=√2/2
aplici  formula  cos2α=2cos²α-1 =>
cos 2*π/8=2*cos²π/8-1=√2/2=>
2 cos²π/8=√2/2+1    relatia  1)=>
cosπ/8=√1/2*[(√2/2+1)]
Din  1)  =.>
cos²π/8=1/2*[√2/2+1)=>
sin²π/8=1-1/2(√2/2+1)=1/2*(1-√2/2)
sinπ/8=√[1/2*(1-√2/2)]

sin²α+coa²α=1

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