Question

cos 55° cos55° + sin55° sin 55° - ctg 45° вычислить

Answer 1

$cos(55°) cos(55°) + sin(55°) sin(55°) - cot(45°) = \ = cos {}^{2} (55°) + sin {}^{2} (55°) - cot(45°) = \ = 1 - cot(45°) = 1 - 1 = 0$