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Calculation cotangenta a, stiind can sin a = 1 supra 3 si a apartine ( 0, Delta supra 2 )

Răspuns :

sin²a+cos²a=1
sin²a(1+cos²a/sin²a)=1

1/3(1+ctg²a)=1
1+ctg²a=3, ctg²a=2, ctga=+-√2
a∈(0, π/2)⇒ ctg a=√2