Решите пожалуйста: 1. cos(a+p/6) + cos(a-p/6) 2. sin(b+p/3) - sin(b-p/3) 3. sin50 - sin...

Question

Решите пожалуйста:
1. cos(a+p/6) + cos(a-p/6)
2. sin(b+p/3) - sin(b-p/3)
3. sin50 - sin 10/sin20

Answer 1

1. cos(a+p/6) + cos(a-p/6)=2cosacosπ/6=√3cosa
2. sin(b+p/3) - sin(b-p/3)=2sinπ/3cosb=√3cosb
3. (sin50 - sin 10)/sin20=2sin20cos30/sin20=2cos30=√3