Question

I need help on a precalc question, medal and fan:
Find an equation in standard form for the ellipse with the vertical major axis of length 18, and minor axis of length 6.

Please just walk me through it so I know how to do it.

Answer 1

@ganeshie8 can you get someone on here to help me?

Answer 2

@thomaster

Answer 3

@phi

Answer 4

please dude

Answer 5

do you know the generic equation for an ellipse?

Answer 6

x^2/a^2 + y^2/b^2 = 1

Answer 7

ok, and generally the a is the semi major-diameter (1/2 of the longer diameter)

if the y direction is longer, you put the a^2 underneath the y

Answer 8

ok so now what values do I have to plug in?

Answer 9

vertical major axis of length 18,

that is telling you the y direction is the major axis

the 18 is the entire height of the ellipse. you want 1/2 of that for "a"

Answer 10

minor axis of length 6
that is the width of the ellipse. you want 1/2 of that for b

Answer 11

so 9^2 =81
y^2/81 + x^2/b^2 = 1

Answer 12

so far, so good

Answer 13

so now what about b?

Answer 14

I posted about "b" up above.

Answer 15

oh lol sorry, so 3^2 = 9
y^2/81 + x^2/9 = 1?

Answer 16

yes

Answer 17

can you help with another?

Answer 18

@ phi ? Find all polar coordinates of point P where P = (5,-pi/6)