Name ________________________________________ Date __________________ Class__________________
LESSON
10-5
Practice B
Parabolas
Use the Distance Formula to find the equation of a parabola with the
given focus and directrix.
1. F(6, 0), x = −3
2. F(1, 0), x = −4
_________________________________________
________________________________________
Write the equation in standard form for each parabola.
3. Vertex (0, 0), directrix y = −2
4. Vertex (0, 0), focus (9, 0)
_________________________________________
5. Focus (−6, 0), directrix x = 6
________________________________________
6. Vertex (0, 0), focus (0, −3)
_________________________________________
________________________________________
Find the vertex, value of p, axis of symmetry, focus, and directrix of
each parabola. Then graph.
7. x − 1 = −
1 2
y
12
8. y + 2 =
_________________________________________
1
2
( x − 1)
4
________________________________________
__________
Solve.
9. A spotlight has parabolic cross sections.
a. Write an equation for a cross section of the
spotlight if the bulb is 6 inches from the
vertex and the vertex is placed at the origin.
_____________________________
b. If the spotlight has a diameter of 36 inches at
its opening, find the depth of the spotlight if
the bulb is 6 inches from the vertex.
_____________________________
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10-36
Holt Algebra 2
b.
x2
y2
−
=1
100 324
3. a. y = ±1.8x; y = ±1.8x
b. −2
b. The asymptotes are the same.
4. C
1
c. y = − x2
8
5. H
7. y = −
Reading Strategies
1. Vertical; y = ±
3
x
5
1 2
x
12
8. x =
1 2
y
16
9. a. (−2, 0)
b. p = 2
5
2. Horizontal; y = ± x
4
c. x = −2
d. (−2, 2)
3. Vertical; y = ±3x
4. Horizontal; y = ±
1 2
x
4p
6. a. y =
e. y = −2
7
x
9
Practice B
1. x =
1 2 3
y +
18
2
2. x = 0.1y − 1.5
3. y =
1 2
x
8
4. x =
5. x = −
1 2
y
24
1 2
y
36
6. y = −
1 2
x
12
7. Vertex (1, 0); p = −3; axis of symmetry y =
0; focus (−2, 0); directrix x = 4
5. Vertical; y = ±4x
8. Vertex (1, −2); p = 1; axis of symmetry x =
1; focus (1, −1); directrix y = −3
LESSON 10-5
Practice A
1.
a.
( x − 0)
b. y =
2
+ ( y − 4) =
2
(x − x)
2
+ ( y − 3)
2
x2 + 7
2
2. y = −
1 2
x +3
8
2
4. y = −0.1x − 2.5
3. x =
1 2 1
y +
6
2
9. a. y =
2
5. x = −0.25y − 3
1 2
x
24
b. 13.5 inches
Original content Copyright © by Holt McDougal. Additions and changes to the original content are the responsibility of the instructor.
A31
Holt Algebra 2