conic sections: Circle, ellipse, parabols

Write the equation of a circle with center (7, 0) with radius 3.

• (x - 7)² + y² = 9
• x² + (y -7)² = 9
• (x - 7)² + y² = 3
• x² + (y -7)² = 3

Tags

CCSS.HSG.GPE.A.1

What is the equation of the circle?

• (x+1)² + (y +1)² = 3
• (x+1)² + (y -1)² = 3
• (x+1)² + (y +1)² = 9
• (x-1)² + (y -1)² = 9

Tags

CCSS.HSG.GPE.A.1

What is the radius of the circle with this equation x² + y² - 10x + 8y - 23 = 0?

• 4

• 2

• 8

• 23

Tags

CCSS.HSG.GPE.A.1

A circle has the equation x² + y² + 8x - 20 = 0. Write the equation in standard form.

• (x + 4)² + y² = 6

• (x + 4)² + y² = 36

• (x - 4)² + y² = 6

• (x - 4)² + y² = 36

Tags

CCSS.HSG.GPE.A.1

The focus is always inside the parabola.

• true
• false

All parabolas with a vertical directrix open the left or right.

• true
• false

(x+3)² = 4(y+5)
What is the equation of the directrix?

• x = 4
• x = 2
• y = -4
• y = -6

Which direction does this parabola open?

• Up
• Down
• Left
• Right

What is the vertex of the parabola: y=2(x-3)²+4

• (3,4)
• (-3,4)
• (3, -4)
• (-3,-4)

The vertex is halfway between the focus and directrix.

• true
• false