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This comprehensive guide delves into classical curves such as rose curves, cardioids, limacons, lemniscates, and spirals. We explore their mathematical definitions, properties, and graphical representations, starting with rose curves using sine and cosine functions. The guide covers the transformation between polar and rectangular coordinates, as well as various equations that represent these curves. Key concepts include intercepts, distances, and the relationship between coefficients and shape characteristics, providing readers with a thorough understanding of these fascinating mathematical shapes.
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r= a sin nθ r= a cos nθ ROSE CURVES SINE: starts Quadrant I COSINE: starts x axis
CARDIOD r= a + a sin nθ r= a + a cos nθ Sine (x axis) Cosine (y axis) a + a (distance point to point) ±a (intercepts)
LIMACON r= a + b sin nθ r= a + b cos nθ a + b (distance shape) b – a (distance loop) ± a intercepts a < b b < a a > 2b loop dimple convex (no shape) Cosine (x axis) Sine (y axis)
LEMNISCATE r2= a sin 2θ r2= a cos 2θ Cosine (x axis) Sine (diagonal)
SPIRAL OF ARCHIMEDES r = aθ More spiral (coefficient decimal/small) Less spiral (coefficient larger)
DESCRIBE EACH R= 3 + 3cosθ R= -2sin3 θ R= -5 + 3cosθ R2= 4cos2θ
RECTANGULAR TO POLAR R (x, y) P (r, θ) R= θ = Arctan (y/x) IF X IS (+) θ = Arctan (y/x) + πIF X IS (-)
POLAR TO RECTANGULAR P (r, θ) R (x, y) X = r cos θ Y = r sin θ
EQUATIONS Complete the square- Substitution- Trig identities! Polar form of x2 + y2 = 16 (r2cos2θ) + (r2sin2θ)= 16 r2 (cos2θ+ sin2θ) = 16 r2 (1) = 16 r= 4 Substitute values of x & y Factor out “r2” Trig identity “cos2θ+ sin2θ=1” Simplify Rectangular form of r=-secθ r= 1 cos θ rcosθ=1 x=1 Rewrite “sec” as “1/cos” Cross multiply Substitute with “x”
To Polar: R (-1,1) R (8, 8√3) X2 + (y + 6)2 = 36 To Rectangular: P(4, π/6) P (-2, π/3) r= 3sinθ