Math Problem Statement

Tentukan persamaan garis singgung pada kurva fungsi dan garis singgungnya pada kurva titik yang diberikan (-1,-1).

Solution

The image contains a question about determining the equation of a tangent line to a curve and graphing it. The vector equation is given as:

r(t)=(cost+cos2t)i+(sint+sin2t)j\mathbf{r}(t) = \left( \cos t + \cos 2t \right) \mathbf{i} + \left( \sin t + \sin 2t \right) \mathbf{j}

The task is to find the tangent line to the curve at the point (-1, -1), where r(t)\mathbf{r}(t) represents a parametric curve.

To approach the problem:

  1. Differentiate r(t)\mathbf{r}(t) to find the tangent vector. [ \mathbf{r}'(t) = \frac{d}{dt}\left[\cos t + \cos 2t \right]\mathbf{i} + \frac{d}{dt}\left[\sin t + \sin 2t \right]\mathbf{j} ]

    [ \mathbf{r}'(t) = \left[-\sin t - 2\sin 2t \right]\mathbf{i} + \left[\cos t + 2\cos 2t \right]\mathbf{j} ]

  2. Find the value of tt that gives the point (-1, -1). This is solved by setting the parametric equations equal to the given coordinates:

    • cost+cos2t=1\cos t + \cos 2t = -1
    • sint+sin2t=1\sin t + \sin 2t = -1

    Solving this system will provide the value of tt at which the tangent is to be calculated.

  3. Substitute the value of tt into r(t)\mathbf{r}'(t) to get the tangent vector at that point.

  4. Write the parametric equation of the tangent line using the point (-1, -1) and the tangent vector found in step 3.

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Math Problem Analysis

Mathematical Concepts

Parametric Equations
Differentiation
Tangent Line

Formulas

r(t) = (cos t + cos 2t) i + (sin t + sin 2t) j
r'(t) = [-sin t - 2sin 2t] i + [cos t + 2cos 2t] j

Theorems

Differentiation of parametric equations
Tangent line at a given point

Suitable Grade Level

Grades 10-12