Question

considerando que seno de 20º= 7/20, quanto vale sec 70º?

Answer 1

sen20 = sen(90-70)

sen20 = sen90.cos70 - sen70.cos90

sen20 = 1.cos70 - sen70.0

sen20 = cos70 = 7/20

Então :

sec70 = 1/cos70

sec70 = 1/7/20

sec70 = 20/7