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Today in Precalculus Go over homework
Connection between polar and rectangular graphs of trig functions Notes: More on Graphs of Polar Equations Homework
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y = 4cos(2x) b. y = 2 + 2sin(x) Range: [-4,4] Range: [0,4] Max. r value:4 Max r value: 4
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Conclusions Rose curve equations are sin or cos waves in rectangular form with changes only to the amplitude and period. Therefore the range of a rose curve is symmetric to zero. Limacon curve equations are sin or cos waves in rectangular form with changes to the amplitude and vertical shift. Therefore the range of a limacon curve is not symmetrical to zero.
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What happens when the “a” is negative in a rose curve?
r = 2 sin3θ r = -2sin3θ If n is odd, the graph is reflected over the x-axis. If n is even, the graph doesn’t change. The points plot in a different order.
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What happens when the “a” is negative in a rose curve?
r = 2 cos3θ r = -2cos3θ If n is odd, the graph is reflected over the y-axis. If n is even, the graph doesn’t change. The points plot in a different order.
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What happens when the “b” is negative in a limacon curve?
r = 1 + 2sinθ r = 1 – 2 sinθ When b is positive, the majority of the curve is around the positive y-axis When b is negative, the majority of the curve is around the negative y-axis.
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What happens when the “b” is negative in a limacon curve?
r = 1 + 2cosθ r = 1 – 2cosθ When b is positive, the majority of the curve is around the positive x-axis When b is negative, the majority of the curve is around the negative x-axis.
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Rose curve Petal length = 3 Petals on all axis, so cos 4 petals so n =2 r = 3cos2θ
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Dimpled limacon Majority of graph over negative x-axis, so negative cos Max r value = 5 = a+b a – b = 1 (where the dimple is) b=2 a=3 r = 3 – 2cosθ
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Limacon with inner loop
Majority of graph over negative y-axis, so negative sin Max r value = 5 = a+b a – b = -1 (where the loop touches) r = 2 – 3sinθ
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Rose curve Petal length = 2 One petal on y-axis, so sin Five petals, n = 5 5 petals should have one petal on positive y-axis, so sin negative r = -2sin5θ
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Homework Worksheet Polar Quiz Monday, April 11
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