Answer:
tan A = ± 1/√3 or ± 0.58
Step-by-step explanation:
2 ways to solve this question.
1. cos 2A = 1/2 2A = 60° or 300° or 420° or ....
A = 30° or 150° or 210° ....
tan A = tan 30° or tan 150° or ... = ± 1/√3
2. cos 2A = 2 cos²A - 1 1/2 = 2 cos²A - 1 cos²A = 3/4
cos 2A = 1 - 2 sin²A 1/2 = 1 - 2 sin²A sin²A = 1/4
tan²A = sin²a/cos²A = (1/4) / (3/4) = 1/3
tan A = ± 1/√3 or ± 0.58
