Представьте в виде произведения sin40+sin16 sin20-sin40 cos46-cos74 cos15+cos45 sin2P/5+sinP/5
Sin40+sin16=2sin28cos12 2. -2sin10cos30 3. cos46-cos74=2sin14sin60 4. cos15+cos45=2cos30cos15 5. sin2π/5+sinπ/5=2sin3π/10cos π/10 6. cos11π/12+cos9π/12=2cos10π/12cosπ/12 7. cos(π/3-a)+cosa=2cosπ/6*cos(π/6-a)=2 8. sin(π/6+a)-sin(π/6-a)=2sina*cosπ/6