Question

Помогите срочно пожалуста геометрия

Answer 1

Ответ:

Объяснение:

1) ∠B = 180°-∠A-∠C = 180°-74°-39° = 67°

теорема синусов:

sinA/BC = sinB/AC = sinC/AB

AC = AB*sinB/sinC = 12*sin67°/sin39°

BC = AB*sinA/sinC = 12*sin74°/sin39°

2)∠A = 180°-∠B-∠C = 180°-21°-56° = 103°

теорема синусов:

sinA/BC = sinB/AC = sinC/AB

AC = BC*sinB/sinA = 6*sin21°/sin103°

AB = BC*sinC/sinB = 12*sin56°/sin21°

3) теорема косинусов :

a^2 = b^2 + c^2- 2bc*cosα

AB^2 = AC^2 +BC^2 -2AC*BC*cosα

AB^2 = 49+81-126*cos80°

AB = √(130-126*cos80°)

теорема синусов:

sinA/BС = sinB/AC = sinC/AB

sinB = AC*sinC/AB

sinB = 7*sin80°/√(130-126*cos80°)

B = arcsin(7*sin80°/√(130-126*cos80°))

sinA = BC*sinC/AB

sinA = 9*sin80°/√(130-126*cos80°)

A= arcsin(9*sin80°/√(130-126*cos80°))

4) теорема косинусов:

a^2 = b^2 + c^2- 2bc*cosα

cosC=(BC^2+AC^2−AB^2)/2BCAC=(81+64−36)/(2⋅9⋅8) = 109/144

C = arccos(109/144)

cosA=(-BC^2+AC^2+AB^2)/2ABAC=(36+64−81)/(2⋅6⋅8) = 19/96

A = arccos(19/96)

B = 180° - arccos(19/96) -  arccos(109/144)