34.5k views
5 votes
Please help precalculus

Please help precalculus-example-1

1 Answer

4 votes

We have Law of Cosines for a and then for the two angles, really only one angle because they'll add to 180 degrees.

b=9, c=11, A=56°

a² = b² + c² - 2bc cos A

a² = 9² + 11² - 2(9)(11) cos(56) ≈ 91.2798

a ≈ 9.554

b² = a² + c² - 2ac cos B

2ac cos B = a² +c² - b²

cos B = (a² +c² - b²) / 2ac

cos B ≈ (91.2798 + 11² - 9²) / 2(9.554)(11) ≈ 0.62458

B ≈ arccos 0.62458 ≈51.348 degrees

Looking at the choices we don't need to bother with C,

Answer: A a=9.6, B=51.4 deg

User Roman Liutikov
by
7.9k 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