105k views
2 votes
How do you solve this

How do you solve this-example-1
User John In MD
by
8.2k points

1 Answer

7 votes

Answer:

Θ ≈ 103°

Explanation:

using the Cosine rule in Δ ABC

cosB =
(a^2+c^2-b^2)/(2ac)

where a is the side opposite ∠ A , b the side opposite ∠ B and c the side opposite ∠ C

here a = 42 , b = 78 and c = 57 , then

cos B =
(42^2+57^2-78^2)/(2(42)(57))

=
(1764+3249-6084)/(4788)

=
(5013-6084)/(4788)

=
(-1071)/(4788) , then

B = Θ =
cos^(-1) ( -
(1071)/(4788) ) ≈ 103° ( to the nearest degree )

User Kareem Kamal
by
8.3k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories