3. = ctg(10 pi + 3pi/4) * cos(14 pi + pi/3) * sin(8pi - 5pi/6) =
= ctg 3pi/4 * cos pi/3 * sin(- 5pi/6) = - 1 * 1/2 * (-1/2) = 1/4 = 0,25.
4.= (sin^2( 3pi + 55) - sin^2 35) / (sin(360 - 10) *cos(360+10)=
=(sin^2 55 - sin^2 35) / ( - sin10 * cos 10)=
= (cos^2 35 - sin^2 35) / (- 1/2 * sin20) = - 2 cos(2*35) / sin 20 = - 2 cos 70 / cos 70 = - 2.
5. = (cos20*cos40 + sin20* sin40) /(sin 20* cos 10 + cos 20*sin 10) =
=(cos40*cos20 + sin40* sin20) / (sin(20+10) =
=(cos(40 - 20)) / sin 30 =cos 20 / 1/2 = 2 cos 20