Вычислите: a] sin 15° b] cos88° cos2° - sin88° sin2° c] sin50° cos5° - cos50° sin5°

Question

Вычислите:

a] sin 15°

b] cos88° cos2° - sin88° sin2°

c] sin50° cos5° - cos50° sin5°

Answer 1

a) sin15*=sin(45-30)=sin45*cos30* - cos45*sin30= sqrt(2)/2 * sqrt(3)/2 - sqrt(2)/2* 1/2= sqrt(2) (sqrt(3)-1))/4

 

b) cos(88+2)=cos(90*)=0

c) sin(50-5)=sin(45*)=sqrt(2)/2