General equations for a circle Prove that the equations
X = a cos t + b sin t, y = c cos t + d sin t
where a, b, c, and d are real numbers, describe a circle of radius R provided a² +c² =b² +d² = R² and ab+cd=0.
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General equations for a circle Prove that the equations
X = a cos t + b sin t, y = c cos t + d sin t
where a, b, c, and d are real numbers, describe a circle of radius R provided a² +c² =b² +d² = R² and ab+cd=0.
14–18. Parametric descriptions Write parametric equations for the following curves. Solutions are not unique.
The circle x ² + y ² =9, generated clockwise
58–59. Tangent lines Find an equation of the line tangent to the following curves at the given point. Check your work with a graphing utility.
x²/16 - y²/9 = 1; (20/3, -4)
53–57. Conic sections
d. Make an accurate graph of the curve.
x = 16y²
51–52. {Use of Tech} Arc length of polar curves Find the approximate length of the following curves.
The limaçon r=3−6cosθ
Polar conversion Consider the equation r=4/(sinθ+cosθ).
a. Convert the equation to Cartesian coordinates and identify the curve it describes.