# Class 12 RD Sharma Solutions- Chapter 19 Indefinite Integrals – Exercise 19.7

• Last Updated : 13 Jan, 2021

### Question 1. ∫sin4x cos7x dx

Solution:

Let I=

We know,

Applying this formula to the given question we get

I=

=

=

We know,

Applying this formula to the given question we get

I=

I=

### Question 2. ∫ cos3x cos4x dx

Solution:

Let I=

Multiplying and dividing the equation by 2,we get

I=

We know,

Applying this formula to the given question we get

I=

=

We know,

and

Applying these formulas to the given question we get

I=

I=

### Question 3. ∫cosmx cosnx dx, m≠​n

Solution:

Let I=

Multiplying and dividing the equation by 2,we get

I=

We know,

Applying this formula to the given question we get

I=

We know,

Applying these formulas to the given question we get

I=

### Question 4. ∫ sinmx cosnx dx, m≠n

Solution:

Let I=

Multiplying and dividing the equation by 2,we get

I=

We know,

Applying this formula to the given question we get

I=

We know,

Applying these formulas to the given question we get

I=

My Personal Notes arrow_drop_up