Circle Coordinates Practice

What the coordinates of 180° on the unit circle?

• 0, 1

• 1, 0

• -1, 0

• 0, -1

What are the coordinates of  210° on the unit circle?

• (−√3/2, −1/2)

• (√3/2, −1/2)

• (−√3/2, 1/2)

• (−1/2,−√3/2 )

What the coordinates of 270° on the unit circle?

• 0, 1

• 1, 0

• -1, 0

• 0, -1

What are the coordinates of 60° on the unit circle?

• (0, 1)

• (1/2, √3/2)

• (√3/2, 1/2)

• (√2/2, 1/2)

There was an earthquake in a city. It was felt up to 80 miles from its epicenter. If the epicenter can be located at the point (15, 8) on a coordinate plane, which equation would help to find the boundary of the area that is affected by the earthquake?

• (x – 15)² + (y – 8)² = 80

• (x – 15)² + (y – 8)² = 289

• (x + 15)² + (y + 8)² = 529

• (x – 15)² + (y – 8)² = 80²

What is the equation for this circle?

• (x+1)+(y+1)=9

• x²+y²=9

• x+y=9

Answer explanation

The correct equation for a circle is x²+y²=r², where r is the radius. In this case, the equation x²+y²=9 represents the circle with a radius of 3.

Which equation represents a circle with a radius of 12 and a center of (1,-2).

Determine the equation of a circle with center (5,-3) and radius of 9

• x²+y²-10x+6y-47=4

• x²+y²-10x-6y-47=0

• 2x²+y²+10x+6y-47=0

• x²+y²-10x+6y-47=0

Answer explanation

The equation of a circle with center (5,-3) and radius of 9 is x^2 + y^2 - 10x + 6y - 47 = 0.