Answer: 14) 44° 15) 6.5
Explanation:
Law of Cosines: a² = b² + c² - 2bc · cos A
Note: The letters can be swapped
14) Given: a = 7, b = 6, c = 10, A = ???
7² = 6² + 10² - 2(6)(10) · cos A
49 = 36 + 100 - 120 cos A
49 = 136 - 120 cos A
-87 = - 120 cos A
0.725 = cos A
43.5° = A
15) Given: A = 21°, b = 18, c = 16
a² = 18² + 16² - 2(18)(16) · cos 21°
= 324 + 256 - 576 cos 21°
= 580 - 576 cos 21°
= 42.26
= 6.5