Ответы на вопрос:
1)sin105*cos105 = sin(90+15)*cos(90+15) = sin15*(-cos15) = -1/2 sin30 = = -1\4. 2)cos75 + sin75 = √2 cos(45-75) = √2cos(-30) = √2cos(+30) = √2√3/2 = =√(3/2) - не 1 можно по другому варианту: cos75+sin75 = cos(90-15) + sin75 = sin15 +sin75 = 2 sin((15+75)/2)*cos((15-75)/2) = 2sin45*cos(-30) = 2(√2/2)(√3/2) = = √(3/2) - не 1
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