For each of the described curves, decide if the curve would be more easily given by a polar equation or a Cartesian equation. Then write an equation for the curve.
(a) A line through the origin that makes an angle of π6 with the positive x-axis.
(b) A vertical line through the point (5,5).

Respuesta :

Answer:

(a) This expression would be more easily represented by a Cartesian equation, since distance with respect to origin varies with angle. ([tex]r = f(\theta)[/tex]). The line is represented by [tex]y = 0.577\cdot x[/tex].

(b) This expression would be more easily represented by a Cartesian equation, since distance with respect to origin varies with angle. ([tex]r = f(\theta)[/tex]). The resulting equation is [tex]x = 5[/tex].

Step-by-step explanation:

(a) This expression would be more easily represented by a Cartesian equation, since distance with respect to origin varies with angle. ([tex]r = f(\theta)[/tex]) A straight line is represented by the following expression:

[tex]y = m\cdot x + b[/tex]

Where:

[tex]x[/tex] - Independent variable, dimensionless.

[tex]y[/tex] - Dependent variable, dimensionless.

[tex]m[/tex] - Slope, dimensionless.

[tex]b[/tex] - y-Intercept.

From Analytical Geometry we know that slope is equal to:

[tex]m = \tan \theta[/tex]

Where [tex]\theta[/tex] is the angle of the line with respect to the positive x-axis, measured in radians.

If we know that [tex]\theta = \frac{\pi}{6}\,rad[/tex], then:

[tex]m = \tan \frac{\pi}{6}[/tex]

[tex]m \approx 0.577[/tex]

The y-intercept is found by replacing independent and dependent variables by known point:

[tex]0 = 0.577\cdot (0) + b[/tex]

[tex]b = 0[/tex]

Therefore, the line is represented by [tex]y = 0.577\cdot x[/tex].

(b) This expression would be more easily represented by a Cartesian equation, since distance with respect to origin varies with angle. ([tex]r = f(\theta)[/tex]) A straight vertical line is represented by:

[tex]x = a[/tex]

Since slope becomes indefined by applying the definition used in (a).

Since that line passes through (5, 5), the value of [tex]a[/tex] is 5. Then, the resulting equation is [tex]x = 5[/tex].