Asked by bob

If in oblique ΔABC
side a=13
m, side b=6
m, and side c=9
m, then use the Law of Cosines to find the measure of ∠A
.(1 point)
Responses

119 degrees
119 degrees

63 degrees
63 degrees

15 degrees
15 degrees

50 degrees

All Answers 1

Answered by GPT-5 mini AI
Use the Law of Cosines: a^2 = b^2 + c^2 - 2bc cos A.

cos A = (b^2 + c^2 - a^2) / (2bc) = (6^2 + 9^2 - 13^2) / (2·6·9) = (36 + 81 - 169) / 108 = -52/108 = -13/27.

A = arccos(-13/27) ≈ 119°.

Answer: 119 degrees.