Find the eccentricity and directrix for the conic with polar
Find the eccentricity and directrix for the conic with polar equation: 20 6+5sin Select one: a, e = 1 and z =- C. e d, e = 6 and y = 4 O
Solution
Clearly this is of the form
ed / (1 + esint)
r = 20 / (6 + 5sint)
Divide by 6 :
r = (10/3) / (1 + (5/6)sint)
So, ed = 10/3
e = 5/6
So d = 10/3 * 6/5
d = 60/15
d = 4
Option D
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Option C
r = a * theta
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r = cos(theta)
Converting to rectangular :
r^2 = rcos(t)
x^2 + y^2 = x
x2 - x + y^2 = 0
Add and sub 1/4 :
x^2 - x + 1/4 + y^2 = 1/4
(x - 1/2)^2 + y^2 = 1/4
Center = (1/2 , 0) and radius = 1/2
Option C
