Evaluate:

OR

Evaluate :

Let

&

So, I = I₁ + I₂ + I₃ …(i)

Solving I₁,

We know that,

⇒ I₁ = 12 – 4 = 8

Solving I₂,

We know that,

⇒ I₂ = 9 – 4 = 5

Solving I₃,

We know that,

⇒ I₃ = 4

Putting the values of I₁, I₂, I₃ in Eq. (i), we get

I = 8 + 5 + 4

= 17

OR

Let

Apply the property

Now, let cosx = t

⇒ - sinx dx = dt

⇒ sinx dx = -dt

when x = 0,

then, cos (0) = t ⇒ t = 1

and when x = π,

then, cos (π) = t ⇒ t = -1

Now, we know that,