(Q3) Find the values of e, a, b, and c for r = 21/ 5 - 2 cos theta

Answer:
Choice C
e = 2/5
a = 5
c = 2
[tex]b=\sqrt{21}[/tex]
Step-by-step explanation:
The first step is to write the polar equation in standard form by dividing the numerator and denominator by 5;
[tex]r=\frac{\frac{21}{5} }{1-\frac{2}{5}cos(theta) }[/tex]
The eccentricity is the coefficient of cos theta, thus
e = 2/5
By definition;
e = c/a
Thus;
c = 2
a = 5
Finally;
[tex]b^{2}=a^{2}-c^{2} \\b^{2}=25-4\\ b=\sqrt{21}[/tex]