2)-2/(0.6)
3)5
Объяснение:
1)
tg(b)+ctg(b) = ((sin(b)^2+(cos(b))^2)/(cos(b)*sin(b)) =
1/(sin(b)*cos(b)) = 1/((sin(b+b)+sin(b-b))/2 = 2/(sin(2b))
sin(2b) = +-sqrt(1-cos(2b)), pi<2b<2pi
sin(2b) = -0.6 => tg(b)+ctg(b)=-2/0.6
2)
(tg(3pi/4-a))^2 = 1+(tg(3pi/4-a))^2-1 =
1/(cos(3pi/4-a))^2-1=
1/(cos(3pi/4)cos(a)+sin(3pi/4)sin(a))^2-1=
4/(cos(a)+sin(a))^2-1=
4/((cos(a))^2+2cos(a)sin(a)+(sin(a))^2)-1=
4/(1+sin(2a))-1, тк sin(2a) = -1/3 получается
4/(1-1/3)-1 = 12/2-1=6-1=5
2)-2/(0.6)
3)5
Объяснение:
1)
tg(b)+ctg(b) = ((sin(b)^2+(cos(b))^2)/(cos(b)*sin(b)) =
1/(sin(b)*cos(b)) = 1/((sin(b+b)+sin(b-b))/2 = 2/(sin(2b))
sin(2b) = +-sqrt(1-cos(2b)), pi<2b<2pi
sin(2b) = -0.6 => tg(b)+ctg(b)=-2/0.6
2)
(tg(3pi/4-a))^2 = 1+(tg(3pi/4-a))^2-1 =
1/(cos(3pi/4-a))^2-1=
1/(cos(3pi/4)cos(a)+sin(3pi/4)sin(a))^2-1=
4/(cos(a)+sin(a))^2-1=
4/((cos(a))^2+2cos(a)sin(a)+(sin(a))^2)-1=
4/(1+sin(2a))-1, тк sin(2a) = -1/3 получается
4/(1-1/3)-1 = 12/2-1=6-1=5