First slide

Properties of ITF

Question

$\cos^{- 1} {\frac{1}{\sqrt{2}} (\cos \frac{9 π}{10} - \sin \frac{9 π}{10})} =$

Easy

A

$\frac{3 π}{10}$
B

$\frac{7 π}{10}$
C

$\frac{7 π}{20}$
D

$\frac{17 π}{20}$

Solution

$\cos^{- 1} [\cos (\frac{9 π}{10} + \frac{π}{4})] = \cos^{- 1} [\cos (\frac{23 π}{20})]$
$\begin{array}{l} = \cos^{- 1} [\cos (2 π - \frac{17 π}{20})] \\ = \cos^{- 1} [\cos (\frac{17 π}{20})] = \frac{17 π}{20} \end{array}$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App