Question

Please help me solve this, random answers will be removed.

Answer 1

Answer:

m∠B = 57.5°

Explanation:

Use cosine rule:

a² = b² + c² - 2bc cos(A)

  inserting values

a² = 21² + 13² - 2(21)(13) cos(91)

a² = 619.529

a = √619.529

a = CB = 24.89 km

Then use sine rule:

sin(A)/a = sin(B)/b

sin(91)/24.89 = sin(B)/21

sin(B) = 21sin(91)/24.89

sin(B) = 0.843583...

B = sin⁻¹(0.843583) = 57.52° ≈ 57.5°

Answer 2

Answer:

See below

Step-by-step explanation:

Here is one way .... I showed you how to use Law of cosines in another Q

 use this to find  CB

CB^2 = 13^2 + 21^2 - 2(13)(21) cos 91      <==== solve for CB

THEN use law of SINES to find angle B

sin B / 21  =  sin 91 / CB           (CB you found using law of cosines above)