Question Number 100870 by bramlex last updated on 29/Jun/20

Commented bybemath last updated on 29/Jun/20

π−e = 0.4233  (π−e)^(ln(1−2cos ^2 x))  ≥ (π−e)^0   case(1)⇒ln(1−2((1/2)+(1/2)cos 2x))≤ 0  ln(−cos 2x) ≤ 0 ⇒−cos 2x ≤ 1  cos 2x ≥−1 , ∀x∈R   case(2)⇒−cos 2x > 0 ; cos 2x<0  (π/4) < x < ((3π)/4) ⇒ x ∈ ((π/4), ((3π)/4)) ★