Odpowiedź:
cos330°/ctg120°+sin²225 ° =
cos(360° -30°)/ctg(180°- 60°) + sin²(270° - 45°) =
= cos30°/(-ctg60°) + (- cos²45°) = √3/2 : (- √3/3) + (- √2/2)² =
= √3/2 * (- 3/√3) + 2/4 = - 3/2 + 1/2 = - 2/2 = - 1
Wzory redukcyjne
cos(360° - α) = cosα
ctg(180° - α) = - ctgα
sin(270° - α) = - cosα
