Question

Sin альфа=0,4 90<альфа<180Cos=?Tg=?

Answer 1

Ответ:

cos^ a a = 1 - sin^ a=1-(0,4)^2=1-0,16=0,84

cos a =√0,84=2√21

tg a=sin a/ cos a= 0,4/2√21

Answer 2

Since sin(alpha) = 0.4 and alpha is between 90 and 180 degrees, we know that alpha is in the second quadrant, where the cosine is negative.

To find the cosine of alpha, we can use the identity:

cos^2(alpha) + sin^2(alpha) = 1

Substituting sin(alpha) = 0.4, we get:

cos^2(alpha) + 0.4^2 = 1

Solving for cos(alpha), we get:

cos(alpha) = ± sqrt(1 - 0.4^2)

Since alpha is in the second quadrant, we know that cos(alpha) is negative. Therefore,

cos(alpha) = - sqrt(1 - 0.4^2)

cos(alpha) ≈ -0.9165

To find the tangent of alpha, we can use the identity:

tan(alpha) = sin(alpha) / cos(alpha)

Substituting sin(alpha) = 0.4 and cos(alpha) = -0.9165, we get:

tan(alpha) = 0.4 / (-0.9165)

tan(alpha) ≈ -0.4367