Question

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

Answer 1

Answer:

Choice C

e = 2/5

a = 5

c = 2

Answer 2

Answer:

Choice C

e = 2/5

a = 5

c = 2

$b=\sqrt{21}$

Step-by-step explanation:

The first step is to write the polar equation in standard form by dividing the numerator and denominator by 5;

$r=\frac{\frac{21}{5} }{1-\frac{2}{5}cos(theta) }$

The eccentricity is the coefficient of cos theta, thus

e = 2/5

By definition;

e = c/a

Thus;

c = 2

a = 5

Finally;

$b^{2}=a^{2}-c^{2} \\b^{2}=25-4\\ b=\sqrt{21}$