Step 1: Background
During the early 1970s, the tiger population in India declined sharply due to hunting and habitat destruction. To protect this endangered species, the Government of India launched a major conservation programme.
Step 2: Launch of Project Tiger
Project Tiger was launched on 1st April 1973 by the Government of India under the leadership of then Prime Minister Indira Gandhi.
Step 3: Objective
The main aim was to ensure a viable population of tigers in their natural habitats and protect them from extinction. Initially, 9 tiger reserves were established under this project.
Step 4: Conclusion
Hence, Project Tiger was started in:
\[
\boxed{1973}
\]
| List I (Biosphere Reserve) | List II (States) | ||
| A. | Agasthyamalai | I. | Madhya Pradesh |
| B. | Nanda Devi | II. | Odisha |
| C. | Panchmarhi | III. | Tamil Nadu |
| D. | Similipal | IV. | Uttarakhand |

The value of $\dfrac{1+\cot^2 \theta}{1+\tan^2 \theta}$ will be: