Q73 / 180 · KCET 2021 · Mathematics
The value of $\cos 1200^{\circ}+\tan 1485^{\circ}$ is
- Correct answerA$\frac{l}{2}$
- B$\frac{3}{2}$
- C$-\frac{3}{2}$
- D$-\frac{1}{2}$
Solution
Given, $\cos 1200^{\circ}+\tan 1485^{\circ}$
$\begin{aligned}
&=\cos 1200^{\circ}+\tan 1485^{\circ} \\
&=\cos \left(3 \times 360^{\circ}+120^{\circ}\right)+\tan \left(4 \times 360^{\circ}+45^{\circ}\right) \\
&=\cos \left(120^{\circ}\right)+\tan \left(45^{\circ}\right) \\
&=\cos \left(180^{\circ}-60^{\circ}\right)+1 \\
&=-\cos 60^{\circ}+1 \\
&=-\frac{1}{2}+1=\frac{1}{2}
\end{aligned}$
Hence, the correct answer is option: 'A'.