Answer:
Step-by-step explanation:
LHS = (sec x - tan x)(Sec x - tan x)
= sec² x - tan²x {(a +b)(a-b) = a² - b²}
[tex]= \dfrac{1}{Cos^{2} \ x}-\dfrac{Sin^{2} \ x}{Cos^{2} \ x}\\\\\\= \dfrac{1-Sin^{2} \ x}{Cos^{2} \ x}\\\\= \dfrac{Cos^{2} \ x}{Cos^{2} \x}\\\\= 1[/tex]
Hence proved.
