Change the following sentences into passive where possible. 1. has anybody sent for dr. smith? 2. she likes her hair long. 3. walter didn't give us any explanation of his strange conduct. 4. they gave us no choice. 5. nobody promised me anything. 6. ray always expresses himself very clearly. 7. dr. ross is performing an operation. 8. many people attended the concert. 9. miss robinson dictated the words to us. 10. the nurse told her nothing. 11. nobody commented on the statement. 12. he became a pilot. 13. nobody tells us anything. 14. they served coffee in the dining-room. 15. everyone had a lovely time at the party. 16. the egyptians played a game like checkers in 1600 b.c. 17. dad caught the largest fish. 18. susan tamed the bird. 19. the boat stopped for repairs. 20. our department manager hired twopart-timers.

Сначала формулы . затем формулы двойного угла sin2α=2sinαcosα cos2α=cos²α-sin²α=cos²α-(1-cos²α)=2cos²α-1⇒  2cos²α=1+cos2α cos2α=cos²α-sin²α=1-sin²α-sin²α=1-2sin²α⇒  2sin²α=1-cos2α а) сos75°cos105°=cos(90°-15°)·cos(90°+15°)== sin15°(-sin15°)=-sin²15°=-(1-cos30°)/2=(cos30°-1)/2= ((√3/2)-1)/2=0,25√3-0,5б) sin75°sin15°=°sin(90°-15°)sin15°=cos15° sin15°=sin30°/2=1/4=0,25в) sin105°cos15°=sin(180°-75°)cos15°=sin75°cos15°=sin(90°-15°)cos15°=cos15°cos15°=(1+cos30°)/2=(1+(√3/2))/2=0,5 +0,25√3 2 способ формулы cosα·cosβ=0,5cos(α-β)+0,5cos(α+β) sinα·sinβ=0,5cos(α-β)-0,5cos(α+β) sinα·cosβ=0,5sin(α+β)+0,5sin(α-β) а) сos75°cos105°=0,5cos(75°-105°)+0,5cos(75°+105°)=0,5cos(-30°)+0,5 cos180°==0,5· √3/2+0,5·(-1)=0,25√3-0,5б) sin75°sin15°=0,5cos(75°-15°)-0,5cos(75°+15° )=0,5cos60°-0,5 cos90°=0,5·0,5=0,25в) sin105°cos15°=0,5sin(105°+15°)+0,5sin(105°-15°)= =0,5sin120°+0,5sin90°==0,5 sin(180°-60°)+0,5·1=0,5 sin 60°+0,5=0,25√3+0,5

A)=сos(90-15)*cos(90+15)=cos15*(-cos15)=-cos²15=-(1+cos30)/2=-(1+√3/2)/2= =-(4+√3)/4 б)=sin(90-15)sin15=cos15sin15=1/2sin30=1/2*1/2=1/4 в)=sin(90+15)cos15=cos15cos15=cos²15=(1+cos30)/2=(1+√3/2)/2=(4+√3)/4