1) sin2α = 2sinα * costgα = sinα / cos3/4 = sinα / cossinα = 3, cosα = 4
sin2α = 2 sinα cossin2α = 2 3/4 sin2α = 6
Ответ: sin2α = 6
2) cos2α = cos^2 α - sin^2 cos2α = cos^2 α - (1 - cos^2 α) (since sin^2 α = 1 - cos^2 αcos2α = cos^2 α - 1 + cos^2 cos2α = 2cos^2 α - 1
cos2α = 2 (4/5)^2 - cos2α = 2 16/25 - cos2α = 32/25 - cos2α = 32/25 - 25/2cos2α = 7/25
Ответ: cos2α = 7/25
1) sin2α = 2sinα * cos
tgα = sinα / cos
3/4 = sinα / cos
sinα = 3, cosα = 4
sin2α = 2 sinα cos
sin2α = 2 3/4
sin2α = 6
Ответ: sin2α = 6
2) cos2α = cos^2 α - sin^2
cos2α = cos^2 α - (1 - cos^2 α) (since sin^2 α = 1 - cos^2 α
cos2α = cos^2 α - 1 + cos^2
cos2α = 2cos^2 α - 1
cos2α = 2 (4/5)^2 -
cos2α = 2 16/25 -
cos2α = 32/25 -
cos2α = 32/25 - 25/2
cos2α = 7/25
Ответ: cos2α = 7/25