1) cos105cos5 + sin105cos85--------------------------------------------=sin195cos5 + cos195sin1852)sin75cos5 - cos75cos85---------------------------------------=cos375cos5 - sin15sin365

решение приведено во вложении

cos105cos5 + sin105cos85          cos105cos5 + sin105cos(90-5)          --------------------------------------------=    --------------------------------------------------------------= sin195cos5 + cos195sin185         sin(105+90)cos5 + cos(105+90)(sin180+5)       cos105cos5 + sin105sin5 = -------------------------------------------- =1     cos105cos5 + (-sin105)(-sin5) 2)sin75cos5 - cos75cos85       sin(90-15)cos5 - cos(90-15)cos(90-5)     --------------------------------------- = -------------------------------------------------------- = cos375cos5 - sin15sin365       cos(360+15)cos5 - sin15sin(360+5)      cos15cos5 - sin15sin5 = ----------------------------------- =1     cos15cos5 - sin15sin5