# NCERT Class 11-Math՚S: Exemplar Chapter 3 Trigonometric Functions Part 11 (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Question 10**:

If

**Answer**:

Given,

As we have to prove:

if we find out the expression of sin and tan in terms of and , we can get the desired expression to be proved.

Adding equation 1 and 2 to get the value of .

Similarly, on subtracting equation 2 from 1, we get-

Multiplying equation 3 and

Hence,

**Question 11**:

If then prove that

**Answer**:

To prove:

We know that:

Hence,

**Question 12**:

If then prove that

**Answer**:

To Prove:

Given,

t:

Hence,

**Question 13**:

If then show that [Hint: Use componendo and Dividendo]

**Answer**:

To prove:

Given,

Applying componendo – dividendo rule, we get-