Which of the following integrals is equivalent to
$$\int \sin^{2}3x\,dx?$$
A - HSC - SSCE Mathematics Extension 1 - Question 2 - 2021 - Paper 1
Question 2
Which of the following integrals is equivalent to
$$\int \sin^{2}3x\,dx?$$
A. \int \frac{1 + \cos 6x}{2}\,dx
B. \int \frac{1 - \cos 6x}{2}\,dx
C. \int \frac{1 +... show full transcript
Worked Solution & Example Answer:Which of the following integrals is equivalent to
$$\int \sin^{2}3x\,dx?$$
A - HSC - SSCE Mathematics Extension 1 - Question 2 - 2021 - Paper 1
Step 1
Evaluate the Integral
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Answer
To solve the integral ∫sin23xdx, we can use the identity:
sin2θ=21−cos(2θ).
Substituting (\theta = 3x), we have:
sin23x=21−cos(6x).
Thus, we rewrite the integral as:
∫sin23xdx=∫21−cos(6x)dx.
Step 2
Identify the Equivalent Integral
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Answer
From the evaluation above, we see that:
∫21−cos(6x)dx
equals option B:
B. \int \frac{1 - \cos 6x}{2},dx.