All Exams Test series for 1 year @ ₹349 only
Question

If $\tan\theta = \frac{7}{8}$, then evaluate $\frac{(1 + \sin\theta)(1 - \sin\theta)}{(1 + \cos\theta)(1 - \cos\theta)(\cot\theta)}$:

The correct answer is
$\frac{8}{7}$

Given:

tanθ = 7/8

⇒ Assume in a right triangle:

height = 7, base = 8, hypotenuse = √113

sinθ = 7/√113, cosθ = 8/√113, cotθ = 8/7

Now the expression:

[(1 + sinθ)(1 − sinθ)] / [(1 + cosθ)(1 − cosθ)(cotθ)]

= (1 − sin²θ) / [(1 − cos²θ)(cotθ)]

= cos²θ / [sin²θ · cotθ]

= cos²θ / [sin²θ · (cosθ/sinθ)]

= cos²θ / (sinθ cosθ)

= cosθ / sinθ

= cotθ

= 8/7

Thus the answer = 8/7

Was this answer helpful?

Important Questions from Trigonometric Identities

  1. What is cos 2β equal to ?

  2. What is the value of sec2γ?

  3. On simplifying \(\frac{{{{\sin }^3}{\rm{A}} + \sin 3{\rm{\;A}}}}{{\sin {\rm{A}}}} + \frac{{{{\cos }^3}{\rm{A}} - \cos 3{\rm{\;A}}}}{{\cos {\rm{A}}}}\) we get

  4. (1 – sin A + cos A) 2is equal to

  5. What is \(\frac{{\cos {\rm{\theta }}}}{{1 - \tan {\rm{\theta }}}} + \frac{{\sin {\rm{\theta }}}}{{1 - \cot {\rm{\theta }}}}\) equal to?

Need Expert Advice?

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App