Which of the following gives the polar form of the equation [tex]2x^2 + 2y^2 = 3x[/tex]?

Select the correct answer below:
A. [tex]r = \frac{3}{2} \cos \theta[/tex]
B. [tex]r = \frac{3}{2} \sin \theta[/tex]
C. [tex]r = \sqrt{\frac{3}{2} \sin \theta}[/tex]
D. [tex]r = \sqrt{\frac{3}{2} \cos \theta}[/tex]



Answer :

To find the polar form of the equation [tex]\( 2x^2 + 2y^2 = 3x \)[/tex], we need to convert the Cartesian coordinates [tex]\((x, y)\)[/tex] to polar coordinates [tex]\((r, \theta)\)[/tex].

1. Recall the relationships between Cartesian and polar coordinates:
[tex]\[ x = r \cos(\theta) \][/tex]
[tex]\[ y = r \sin(\theta) \][/tex]

2. Substitute these relationships into the given Cartesian equation:
[tex]\[ 2(r \cos(\theta))^2 + 2(r \sin(\theta))^2 = 3(r \cos(\theta)) \][/tex]

3. Simplify the equation step-by-step:
[tex]\[ 2r^2 \cos^2(\theta) + 2r^2 \sin^2(\theta) = 3r \cos(\theta) \][/tex]

4. Use the Pythagorean identity, [tex]\(\cos^2(\theta) + \sin^2(\theta) = 1\)[/tex]:
[tex]\[ 2r^2 (\cos^2(\theta) + \sin^2(\theta)) = 3r \cos(\theta) \][/tex]
[tex]\[ 2r^2 \cdot 1 = 3r \cos(\theta) \][/tex]
[tex]\[ 2r^2 = 3r \cos(\theta) \][/tex]

5. Solve for [tex]\( r \)[/tex]:
[tex]\[ r = \frac{3}{2} \cos(\theta) \][/tex]

Therefore, the polar form of the equation [tex]\( 2x^2 + 2y^2 = 3x \)[/tex] is:
[tex]\[ r = \frac{3}{2} \cos(\theta) \][/tex]

The correct answer is:
[tex]\[ r = \frac{3}{2} \cos \theta \][/tex]

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