Tq2x =tqx , x ∈ [ 0 ; 45°] * * * x ∈ [ 0 ; π/4] * * *
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tq2x =tqx ;
2tqx /(1 -tq²x) =tqx ;
(tqx)*( 2/(1 -tq²x) - 1) =0 ;
(tqx)*(tq²x+1) / (1 - tq²x) = 0 ⇔ tqx =0 ⇔ x = π*k , k ∈ Z.
0 ≤ π*k ≤ π/4 ⇔ 0 ≤ k ≤ 1/4 ⇒ k =0.
ответ : 0 .
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* * * tq²x+1 ≥ 1 * * *