Trigonometric Identities Exercise 18

ML Aggarwal Solutions Class 10 Mathematics Solutions for Trigonometric Identities Exercise 18 in Chapter 18 - Trigonometric Identities

Question 18 Trigonometric Identities Exercise 18

(sec A – 1)/(sec A + 1) = (1 – cos A)/(1 + cos A)

Answer:

In LHS, we can convert sec A in terms of cos A.

$\begin{aligned} =& \frac{\frac{1-\cos \mathrm{A}}{\cos \mathrm{A}}}{\frac{1+\cos \mathrm{A}}{\cos \mathrm{A}}}=\frac{1-\cos \mathrm{A}}{\cos \mathrm{A}} \times \frac{\cos \mathrm{A}}{1+\cos \mathrm{A}} \\ =& \frac{1-\cos \mathrm{A}}{1+\cos \mathrm{A}}=\mathrm{R} . \mathrm{H} . \mathrm{S} . \end{aligned}$

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