Answer:
Step-by-step explanation:
let s estimate the following
[tex](secA-tanA)(secA+tanA)=sec^2A-tan^2A=\dfrac{1}{cos^2A}-\dfrac{sin^2A}{cos^2A}=\dfrac{1-sin^2A}{cos^2A}=\dfrac{cos^2A}{cos^2A}=1[/tex]
as [tex]cos^2A+sin^2A=1[/tex]
it means that
[tex]\dfrac{1}{secA-tanA}=secA+tanA[/tex]
hope this helps
