Sin a = 1 / 4.
cos a - ?
tg a - ?
Решение:
sin²a + cos²a = 1,
cos²a = 1 - sin²a,
cos²a = 1 - (1 / 4)² = 1 - (0,25)² = 1 - 1/16 = 15/16,
cos a = cos²a : 2, cos a = (15/16) : 2 = 15 / 32.
tg a = sin a / cos a = (1/14) / (15/32) = 16 / 105.
Ответ: cos a = 15 / 32, tg a = 16 / 105.