Question

пожалуйста
помогите

Answer 1

$cos^{2} alpha = 1 - {sin}^{2} alpha = 1 - {0.75}^{2} = 1 - {( frac{3}{4}) }^{2} = 1 - frac{9}{16} = frac{16}{16} - frac{9}{16} = frac{7}{16} \ cos alpha = + - frac{ sqrt{7} }{4}$