This question is taken from RS Aggarwal, chapter – trigonometry, topic – trigonometric identities in which we have given that (secθ+tanθ) = m and (secθ-tanθ) = n
we have to prove that mn = 1 by using trigonometric formulas
Book – RS Aggarwal, Class 10, chapter 13B, question no 4
(secθ+tanθ)=m....(1) and
(secθ−tanθ)=n....(2)
Multiply (1) and (2), we have
⇒(secθ+tanθ)(secθ−tanθ)=mn
⇒(sec²θ−tan²θ)=mn
∴1=mn
Or mn=1
Hence proved