Question

se o senθ 3/4 quanto vale cosθ?

Answer 1

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