UPSC CDS 1 2023 Math Paper

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Question : 46 of 100
 
Marks: +1, -0
Consider the following:
1. cos4⁡θ−sin‌4⁡θ=‌
2‌tan‌⁡θ‌
1−tan‌2⁡θ
,0<θ<‌
π‌
2

2. co sec⁡θ+cot⁡θ=‌
1
co sec‌⁡θ‌−cot‌⁡θ‌} ,0<θ<‌
π‌
2

3. cos2⁡θ−sin‌2⁡θ=‌
1−tan‌2⁡θ‌
1‌+‌tan‌2⁡θ
,0<θ<‌
π‌
2

Which of the above equations are identities?
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