Keerthana
Posted on

If cosθ=12\cos \theta=-\frac{1}{2} and θ\theta lies in third quadrant, then what will be the value of sinθ+tanθ\sin \theta+\tan \theta

a

12\frac{1}{2}

b

23\frac{2}{\sqrt{3}}

c

32\frac{\sqrt{3}}{2}

d

13\frac{1}{\sqrt{3}}

Answer : Option C
Explanation :
Here, cosθ=12\cos \theta=-\frac{1}{2} and θ\theta, lies in third quadrant

Consider ΔABC, Using Pythagoras theorem,

AC2=AB2+BC2\mathrm{AC}^{2}=\mathrm{AB}^{2}+\mathrm{BC}^{2}

22=(1)2+BC22^{2}=(1)^{2}+\mathrm{BC}^{2}

BC2=41\Rightarrow \mathrm{BC}^{2}=4-1

BC2=3\mathrm{BC}^{2}=3

BC=3\mathrm{BC}=\sqrt{3}

tanθ+sinθ=3+{(32)}\tan \theta+\sin \theta=-\sqrt{3}+\left\{-\left(\frac{\sqrt{3}}{2}\right)\right\}

In third quadrant sinθ is negative and tanθ is positive.

=32=\frac{\sqrt{3}}{2}

Rate This:
NaN / 5 - 1 votes
Profile photo for Dasaradhan Gajendra