Finding Parametric Equations

Which parametric equations represent [tex]$(x+1)^2+(y-3)^2=16$ ?

A. [tex]x=8 \cos (t)-1[/tex] and [tex]y=8 \sin (t)+3[/tex]

B. [tex]x=-\cos (t)+8[/tex] and [tex]y=3 \sin (t)+8[/tex]

C. [tex]x=4 \cos (t)-1[/tex] and [tex]y=4 \sin (t)+3[/tex]

D. [tex]x=-\cos (t)+4[/tex] and [tex]y=3 \sin (t)+4[/tex]



Answer :

To find the parametric equations for the given equation [tex]\((x+1)^2 + (y-3)^2 = 16\)[/tex], let's follow a detailed, step-by-step approach:

1. Identify the type of curve represented by the equation:

The given equation [tex]\((x+1)^2 + (y-3)^2 = 16\)[/tex] is in the standard form of the equation of a circle:
[tex]\[ (x - h)^2 + (y - k)^2 = r^2 \][/tex]
where [tex]\((h, k)\)[/tex] is the center of the circle and [tex]\(r\)[/tex] is the radius.

2. Determine key parameters:

By comparing [tex]\((x + 1)^2 + (y - 3)^2 = 16\)[/tex] to the standard form:
[tex]\[ h = -1, \quad k = 3, \quad r^2 = 16 \][/tex]
We find that:
[tex]\[ h = -1, \quad k = 3, \quad r = \sqrt{16} = 4 \][/tex]

3. Recall the parametric equations for a circle:

For a circle centered at [tex]\((h, k)\)[/tex] with radius [tex]\(r\)[/tex], the parametric equations are:
[tex]\[ x = h + r \cos(t) \][/tex]
[tex]\[ y = k + r \sin(t) \][/tex]

4. Substitute the values for [tex]\(h\)[/tex], [tex]\(k\)[/tex], and [tex]\(r\)[/tex]:

Substituting [tex]\(h = -1\)[/tex], [tex]\(k = 3\)[/tex], and [tex]\(r = 4\)[/tex]:
[tex]\[ x = -1 + 4 \cos(t) \quad \text{or} \quad x = 4 \cos(t) - 1 \][/tex]
[tex]\[ y = 3 + 4 \sin(t) \quad \text{or} \quad y = 4 \sin(t) + 3 \][/tex]

5. Combine the parametric equations:

Thus, the parametric equations for the given circle are:
[tex]\[ x = 4 \cos(t) - 1 \][/tex]
[tex]\[ y = 4 \sin(t) + 3 \][/tex]

6. Check the provided options:

Comparing this with the provided options, we see:
[tex]\[ \text{Option 3: } x = 4 \cos(t) - 1 \text{ and } y = 4 \sin(t) + 3 \][/tex]

Hence, the correct parametric equations that represent [tex]\((x+1)^2 + (y-3)^2 = 16\)[/tex] are:
[tex]\[ x = 4 \cos(t) - 1 \quad \text{and} \quad y = 4 \sin(t) + 3 \][/tex]

[tex]\(\boxed{x = 4 \cos (t) - 1 \text { and } y = 4 \sin (t) + 3}\)[/tex]