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)

63 degrees

15 degrees

50 degrees

119 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) = (-52)/108 = -13/27.

A = arccos(-13/27) ≈ 119°.

Answer: 119 degrees.