На фотографии..........
а) sinα = -12/13
cosα = √(1 - (-12/13)²) = √(169/169 - 144/169) = √(25/169) = ±5/13
т.к π < α < 3π/2, то cosα = -5/13
б) tgα = sinα/cosα = -12/13 : (-5/13) = 12/13 * 13/5 = 12/5
На фотографии..........
а) sinα = -12/13
cosα = √(1 - (-12/13)²) = √(169/169 - 144/169) = √(25/169) = ±5/13
т.к π < α < 3π/2, то cosα = -5/13
б) tgα = sinα/cosα = -12/13 : (-5/13) = 12/13 * 13/5 = 12/5