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Using Trigonometric Identities

Trig Identities
  • \(x=\sin(t)+2\)
  • \(y=\cos (t)-3\)

  • \(\sin^2t+\cos^2t=1\)
  • \(x=\sin (t)+2\to \sin t=x-2\)
  • \(y=\cos(t)-3\to \cos t=y+3\)
  • \(\sin^2t+\cos^{2}t=1\to (x-2)^2+(y+3)^2=1\)
  • This equation is a circle ^^^^
\(x=2\sin t\), \(y=1-\cos^{2}t\)
  • Find a cartesian equation for this parametric equation in the form \(y=f(x)\), \(-k\leq x\leq k\)
  • \(1-\cos^2t=1-\cos^2t+\sin^2t\)
  • \(=2\sin^2t\)
  • \(y=\frac{1}{2}x^2\)

\(x=2\sin t\)
Max value of \(\sin t=-1 \text{ and }1\)
Max values of \(2\sin t=-2\text{ and }2\)

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