Answer:
[tex] { \sec} A = \sqrt{1 + { \tan}^{2} A } [/tex]
Step-by-step explanation:
[tex] { \sec}^{2} A = 1 + { \tan}^{2} A \\ \\ \implies \: { \sec} A = \sqrt{1 + { \tan}^{2} A } [/tex]