Arcsinx = π/2 - arccosx (π/2 - arccosx)arccosx ≤ π²/16 -arccos²x + π/2 * arccosx - π²/16 ≤ 0 arccos²x - π/2 * arccosx + π²/16 ≥ 0 (arccosx - π/4)² ≥ 0 - верное неравенство.