Read and write the equation of a circle

Answer Key - Grade 10 Math Worksheet - Building Confidence

Circle the best answer, or write your answer on the line.

2. 1.

   Bo draws a round pizza on a grid as (x + 4)² + (y − 1)² = 9. Where is its center?

   (-4, 1)
3. 2.

   Jun draws a sun shape in a mural on a grid as (x + 1)² + (y + 7)² = 25. Where is its center?

   Use the picture in question 1.

   (-1, -7)
4. 3.

   a circle with center C(2, 5); a radius is drawn as the long side of a right triangle under it. Kira draws a drum top on a grid as (x − 2)² + (y − 5)² = 36. How long is its radius, in units?

   6
5. 4.

   a circle with center C(-3, 4); a radius is drawn as the long side of a right triangle under it. Luz draws a round flower bed in a park on a grid as (x + 3)² + (y − 4)² = 81. How long is its radius, in units?

   9
6. 5.

   a circle with center C(6, -1); a radius is drawn as the long side of a right triangle under it. Milo draws a bike wheel on a grid as (x − 6)² + (y + 1)² = 16. How long is its radius, in units?

   4
7. 6.

   a circle with center C(-2, -5); a radius is drawn as the long side of a right triangle under it. Noah draws a round cake on a grid as (x + 2)² + (y + 5)² = 64. How long is its radius, in units?

   8
8. 7.

   a circle with center C(2, -5); a radius is drawn as the long side of a right triangle under it. Pia draws a round clock face with center (2, -5) and radius 3 on a grid. Which equation is the circle?

   • (x + 2)² + (y − 5)² = 3
   • (x + 2)² + (y − 5)² = 9
   • (x − 2)² + (y + 5)² = 3
   • (x − 2)² + (y + 5)² = 9
9. 8.

   a circle with center C(-1, 4); a radius is drawn as the long side of a right triangle under it. Ren draws a round pizza with center (-1, 4) and radius 6 on a grid. Which equation is the circle?

   • (x + 1)² + (y − 4)² = 36
   • (x − 1)² + (y + 4)² = 6
   • (x − 1)² + (y + 4)² = 36
   • (x + 1)² + (y − 4)² = 6
10. 9.

    a circle with center C(3, 3); a radius is drawn as the long side of a right triangle under it. Tala draws a round pond with center (3, 3) and radius 5 on a grid. Which equation is the circle?

    • (x − 3)² + (y − 3)² = 5
    • (x + 3)² + (y + 3)² = 25
    • (x + 3)² + (y + 3)² = 5
    • (x − 3)² + (y − 3)² = 25
11. 10.

    Zee draws a sun shape in a mural with center (-6, -2) and radius 4 on a grid. Which equation is the circle?

    • (x − 6)² + (y − 2)² = 16
    • (x − 6)² + (y − 2)² = 4
    • (x + 6)² + (y + 2)² = 16
    • (x + 6)² + (y + 2)² = 4