# NCERT Class 11-Math's: Exemplar Chapter 3 Trigonometric Functions Part 9

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**Question 2:**

**Answer:**

As we have to prove:

Given,

As we need to get in numerator, so we need to bring this term in numerator.

Multiplying numerator and denominator by

Using

Thus,

**Question 3:**

[**Hint:** Express and apply componendo and dividendo]

**Answer:**

Given,

To prove:

Applying componendo-dividendo rule –

By transformation formula of T-ratios we know that –

and

On applying formula, we get –

**Question 4:**

If find the value of

**Answer:**

**Question 5:**

If

**Answer:**