Question

найти cos B, tg B и ctg B, если sinB = 4/5

Answer 1

1)

$cos^2x + sin^2x = 1\cos^2x = 1 - sin^2x\cos^2x = 1 - frac{16}{25} = frac{9}{25} \cos(x) = frac{3}{5}$

2)

$tgbeta = frac{sinbeta }{cosbeta } \tgbeta = frac{4}{5} : frac{3}{5} = frac{4 * 5}{5 * 3} =frac{4}{3}$

3)

$ctgbeta = frac{cosbeta }{sinbeta } \ctgbeta = frac{3}{5} : frac{4}{5} = frac{3*5}{5*4} = frac{3}{4} = 0,75$