Question

What are the angles of △ABC with side lengths a=12, b=21, and c=14?

Round each angle to the nearest tenth of a degree and use that rounded value to find the remaining angles.

Answer 1

Answer: the answer is A=33∘, B=107.5∘, and C=39.5∘ is correct or c

Explanation:

To find the angles of triangle ABC with side lengths a=12, b=21, and c=14, we can use the Law of Cosines and then apply the Law of Sines to find the remaining angles. Let's denote the angles as A, B, and C respectively.

According to the Law of Cosines:

c^2 = a^2 + b^2 - 2ab * cos(C)

Plugging in the given side lengths:

14^2 = 12^2 + 21^2 - 2 * 12 * 21 * cos(C)

196 = 144 + 441 - 504 * cos(C)

504 * cos(C) = 389

cos(C) = 389 / 504

C = arccos(389 / 504)

Using a calculator to find the approximate value of C, we get C ≈ 43.5°.