Answer
(a) Focus: $F(0,-1)$
Directrix: $y=1$
$Focal~diameter=4$
(b)
Work Step by Step
Equation of a parabola with vertical axis: $x^2=4py$
$x^2=-4y$
$4p=-4$
$p=-1$
Focus: $F(0,p)=F(0,-1)$
Directrix: $y=-p=1$
$Focal~diameter=|4p|=4$
Precalculus: Mathematics for Calculus, 7th Edition
by Stewart, James; Redlin, Lothar; Watson, Saleem
Published by
Brooks Cole
ISBN 10:
1305071751
ISBN 13:
978-1-30507-175-9
Chapter 11 - Section 11.1 - Parabolas - 11.1 Exercises - Page 788: 12
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