Respuesta :

sec 2 A = 1 / cos 2 A
1 / cos 2 A = 1 / sin 13 A
cos 2 A = sin 13 A
2 A = 90° - 13 A
2 A + 13 A = 90°
15 A = 90°
A = 90° : 15
Answer:
B ) A = 6°