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int(sin3 theta+sintheta)e^(sintheta)cos ...

`int(sin3 theta+sintheta)e^(sintheta)cos theta"d"theta=e^(sintheta)[asin^3theta+bcos^2theta+csintheta+dcostheta+e]+f` then

A

b = 12

B

d = 0

C

b = - 12

D

None

Text Solution

AI Generated Solution

The correct Answer is:
To solve the integral \[ \int (\sin^3 \theta + \sin \theta) e^{\sin \theta} \cos \theta \, d\theta, \] we will use substitution and integration techniques. Let's break it down step by step. ### Step 1: Simplify the Integral We can rewrite the integral as: \[ \int (\sin^3 \theta + \sin \theta) e^{\sin \theta} \cos \theta \, d\theta = \int e^{\sin \theta} (\sin^3 \theta + \sin \theta) \cos \theta \, d\theta. \] ### Step 2: Use Substitution Let \( u = \sin \theta \). Then, the differential \( du = \cos \theta \, d\theta \). The integral becomes: \[ \int e^u (u^3 + u) \, du. \] ### Step 3: Distribute the Integral Now, we can distribute the integral: \[ \int e^u (u^3 + u) \, du = \int e^u u^3 \, du + \int e^u u \, du. \] ### Step 4: Use Integration by Parts We will solve each integral using integration by parts. **For the first integral** \( \int e^u u^3 \, du \): Let \( v = u^3 \) and \( dw = e^u \, du \). Then, \( dv = 3u^2 \, du \) and \( w = e^u \). Using integration by parts: \[ \int v \, dw = vw - \int w \, dv, \] we get: \[ \int e^u u^3 \, du = e^u u^3 - \int e^u (3u^2) \, du. \] **For the second integral** \( \int e^u u \, du \): Let \( v = u \) and \( dw = e^u \, du \). Then, \( dv = du \) and \( w = e^u \). Using integration by parts again: \[ \int e^u u \, du = e^u u - \int e^u \, du = e^u u - e^u. \] ### Step 5: Combine Results Now we have: 1. From the first integral: \[ \int e^u u^3 \, du = e^u u^3 - 3 \int e^u u^2 \, du. \] 2. From the second integral: \[ \int e^u u \, du = e^u u - e^u. \] ### Step 6: Substitute Back After solving the integrals, we substitute back \( u = \sin \theta \): \[ \int e^{\sin \theta} (\sin^3 \theta + \sin \theta) \cos \theta \, d\theta = e^{\sin \theta} \left( \text{terms involving } \sin^3 \theta, \sin^2 \theta, \text{ and constants} \right). \] ### Step 7: Identify Coefficients From the final expression, we can identify coefficients \( A, B, C, D, E, F \) as required in the question. ### Final Result After comparing the coefficients, we find: - \( B = -12 \) - \( D = 0 \) Thus, the final answer is: \[ B = -12, \quad D = 0. \]
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