(Q3)i. If tan X =
5
12
, then find sec x.

Given tan x =
5
12

We know that sec2 x – tan2 x = 1

sec2 x = 1 + 2 x

sec x = √1 + 2 x

= √1 + (
)2 = √1 +
= √
144 +
= √
=