Sin²α = 1 - cos²α = 1 - 49/625 = 576/625 = (24/25)²
При 3π/2 ≤ α ≤ 2π: sin α < 0.
Поэтому sinα = -24/25.
sin 2α = 2 · sin α · cos α = 2 · (-24/25) · 7/25 = -336/625
cos 2α = cos²α - sin²α = (7/25)² - (24/25)² = -527/625
tg 2α = sin 2α / cos 2α = 336/527