Решите примеры ! (какие сможете) 1)sin15cos15-cos15sin5= 2)cos15cos5+sin15sin5= 3)cos15sin5+sin15cos5= 4)tg18+tg48/1-tg18tg12= 5)tg18-tg48/1+tg18tg48= 6)1-tg18tg12/tg18+tg12= 7)sin(α+β)+sin(α+β)= 8)cos(α+β)+cos(α-β)=

2. cos15cos5+sin15sin5=cos(15-5)=cos10
3. cos15sin5+sin15cos5=sin(5+15)=sin20
7. sin(a+b)+sin(a+b)=2sin(a+b)   (?)
8. cos(a+b)+cos(a-b)=cosacosb-sinasinb+cosacosb+sinasinb=2cos(a)cos(b)