Find the equation of the line tangent to the cardioid r = 1+ sin(0) at Ô0 =

Algebra and Trigonometry (MindTap Course List)
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ISBN:9781305071742
Author:James Stewart, Lothar Redlin, Saleem Watson
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Chapter8: Polar Coordinates And Parametric Equations
Section8.CT: Chapter Test
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**Question:**

Find the equation of the line tangent to the cardioid \( r = 1 + \sin(\theta) \) at \( \theta = 0 \).

---

**Solution:**

1. **Convert to Cartesian Coordinates:**

   The polar coordinates \( r \) and \( \theta \) can be converted to Cartesian coordinates \( (x, y) \) using the formulas:
   \[
   x = r \cos(\theta)
   \]
   \[
   y = r \sin(\theta)
   \]

   For the given cardioid \( r = 1 + \sin(\theta) \), we first calculate the coordinates at \( \theta = 0 \).

   \[
   r = 1 + \sin(0) = 1 + 0 = 1
   \]

   \[
   x (0) = 1 \cos(0) = 1 \cdot 1 = 1
   \]
   \[
   y (0) = 1 \sin(0) = 1 \cdot 0 = 0
   \]

   Therefore, the point of tangency in Cartesian coordinates is \( (1, 0) \).

2. **Find the Derivative:**

   To find the slope of the tangent line, we consider the derivatives of \( x \) and \( y \) with respect to \( \theta \).

   \[
   x = r \cos(\theta) = \left(1 + \sin(\theta)\right) \cos(\theta)
   \]
   \[
   y = r \sin(\theta) = \left(1 + \sin(\theta)\right) \sin(\theta)
   \]

   Differentiate \( x \) and \( y \) with respect to \( \theta \):

   \[
   \frac{dx}{d\theta} = \frac{d}{d\theta} \left( (1 + \sin(\theta)) \cos(\theta) \right)
   \]
   Apply the product rule:
   \[
   \frac{dx}{d\theta} = \cos(\theta) \frac{d}{d\theta} (1 + \sin(\theta)) + (1 + \sin(\theta)) \frac{d}{d\theta} \cos(\theta)
   \]
   \[
Transcribed Image Text:**Question:** Find the equation of the line tangent to the cardioid \( r = 1 + \sin(\theta) \) at \( \theta = 0 \). --- **Solution:** 1. **Convert to Cartesian Coordinates:** The polar coordinates \( r \) and \( \theta \) can be converted to Cartesian coordinates \( (x, y) \) using the formulas: \[ x = r \cos(\theta) \] \[ y = r \sin(\theta) \] For the given cardioid \( r = 1 + \sin(\theta) \), we first calculate the coordinates at \( \theta = 0 \). \[ r = 1 + \sin(0) = 1 + 0 = 1 \] \[ x (0) = 1 \cos(0) = 1 \cdot 1 = 1 \] \[ y (0) = 1 \sin(0) = 1 \cdot 0 = 0 \] Therefore, the point of tangency in Cartesian coordinates is \( (1, 0) \). 2. **Find the Derivative:** To find the slope of the tangent line, we consider the derivatives of \( x \) and \( y \) with respect to \( \theta \). \[ x = r \cos(\theta) = \left(1 + \sin(\theta)\right) \cos(\theta) \] \[ y = r \sin(\theta) = \left(1 + \sin(\theta)\right) \sin(\theta) \] Differentiate \( x \) and \( y \) with respect to \( \theta \): \[ \frac{dx}{d\theta} = \frac{d}{d\theta} \left( (1 + \sin(\theta)) \cos(\theta) \right) \] Apply the product rule: \[ \frac{dx}{d\theta} = \cos(\theta) \frac{d}{d\theta} (1 + \sin(\theta)) + (1 + \sin(\theta)) \frac{d}{d\theta} \cos(\theta) \] \[
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