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Ch. 5 - Complex Numbers, Polar Coordinates and Parametric Equations
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601Not the one you use?Change textbook
Chapter 5, Problem 7

In Exercises 1–8, parametric equations and a value for the parameter t are given. Find the coordinates of the point on the plane curve described by the parametric equations corresponding to the given value of t. x = (60 cos 30°)t, y = 5 + (60 sin 30°)t − 16t²; t = 2

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Identify the parametric equations given: \(x = (60 \cos 30^\circ) t\) and \(y = 5 + (60 \sin 30^\circ) t - 16 t^2\).
Substitute the given value of the parameter \(t = 2\) into the equation for \(x\): calculate \(x = (60 \cos 30^\circ) \times 2\).
Substitute the same value \(t = 2\) into the equation for \(y\): calculate \(y = 5 + (60 \sin 30^\circ) \times 2 - 16 \times (2)^2\).
Recall the exact trigonometric values: \(\cos 30^\circ = \frac{\sqrt{3}}{2}\) and \(\sin 30^\circ = \frac{1}{2}\), and use these to simplify the expressions for \(x\) and \(y\).
After substituting and simplifying, write the coordinates of the point as \((x, y)\) corresponding to \(t = 2\).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Parametric Equations

Parametric equations express the coordinates of points on a curve as functions of a parameter, often denoted as t. Instead of y as a function of x, both x and y depend on t, allowing the description of more complex curves and motions.
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Evaluating Trigonometric Functions at Specific Angles

Trigonometric functions like sine and cosine have known values at special angles such as 30°, 45°, and 60°. For example, cos 30° = √3/2 and sin 30° = 1/2. These values simplify calculations when substituting into parametric equations.
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Substitution and Calculation of Coordinates

To find the point on the curve for a given parameter t, substitute the value of t into the parametric equations for x and y. This involves arithmetic operations and applying trigonometric values to compute the exact coordinates of the point.
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