If $\sec x=\frac{25}{24}$ and $x$ lies in first quadrant, then $\sin \frac{x}{2}+\cos \frac{x}{2}=$
If $\sec x=\frac{25}{24}$ and $x$ lies in first quadrant, then $\sin \frac{x}{2}+\cos \frac{x}{2}=$
- $\frac{6}{5 \sqrt{2}}$
- $\frac{8}{5 \sqrt{2}}$
- $\frac{7}{5 \sqrt{2}}$
- $\frac{1}{5 \sqrt{2}}$
Solution
We have $\cos x=\frac{24}{25} \Rightarrow \sin x=\frac{7}{25} \ldots\left[\because x\right.$ lies in $1^{\text {st }}$ quadrant $]$
Also $\left(\sin \frac{x}{2}+\cos \frac{x}{2}\right)^2=1+\sin x=1+\frac{7}{25}=\frac{32}{25}$
$\therefore \sin \frac{x}{2}+\cos \frac{x}{2}=\sqrt{\frac{32}{25}}=\frac{4 \sqrt{2}}{5}=\frac{8}{5 \sqrt{2}}$
Asked in: MHT CET 2021 (20 Sep Shift 2)
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