Circle equations Quiz 1

Question 1

Sona knows the radius of a particular circle is 6 units and the center of the circle is $$(6,0)$$. What will be the equation of the circle?

Accepted Answer

$${{x}^{2}}+{{y}^{2}}-12x=0$$

Answer

$${{x}^{2}}+{{y}^{2}}=4$$

Answer

$${{x}^{2}}+{{y}^{2}}+12x=12$$

Answer

$${{x}^{2}}+{{y}^{2}}-12x=36$$

Question 2

Mohit wishes to draw a circle such that the distance between the center $$(-1,-9)$$ and circumference is $$\sqrt{7}$$. He tries to plot the circle, helping him by finding the equation.

Accepted Answer

$${{x}^{2}}+{{y}^{2}}+2x+18y+75=0$$

Answer

$${{x}^{2}}+{{y}^{2}}=4$$

Answer

$${{x}^{2}}+{{y}^{2}}=24$$

Answer

$${{x}^{2}}+{{y}^{2}}+2x+18y=75$$

Question 3

Sham knows that the equation of the circle is $${{(x-9)}^{2}}+{{(y+4)}^{2}}=25$$. What would be the radius and center of this equation?

Accepted Answer

$$	ext{Center}\equiv (9,-4)$$ and $$	ext{radius = 5 units}$$

Answer

$$	ext{Center}\equiv (9,-4)$$ and $$	ext{radius = 25 units}$$

Answer

$$	ext{Center}\equiv (-9,4)$$ and $$	ext{radius = 25 units}$$

Answer

$$	ext{Center}\equiv (-9,4)$$ and $$	ext{radius = 5 units}$$

Question 4

A scientist working towards her next invention sees that the object is moving in a path denoted by the equation $${{x}^{2}}+{{y}^{2}}+14x-8y+56=0.$$ What can you say about the path of the object, what will be its central point?

Accepted Answer

The equation represents a circle with $$	ext{Center}\equiv (-7,4)$$

Answer

The equation represents an ellipse with $$	ext{Focus}\equiv (9,-4)$$

Answer

The equation represents an ellipse with$$	ext{Center}\equiv (-8,-4)$$

Answer

The equation represents a parabola with $$	ext{Focus}\equiv (-9,4)$$

Question 5

Vinyl discs are to be mass produced in a factory, the machine takes input as equation of circle given by $$9{{x}^{2}}+9{{y}^{2}}-6x-36y-107=0$$ . Imran is a manager asking about the radius of the disc. What would you say to him?

Accepted Answer

The radius of disc is 4 units

Answer

The radius of disc is 8 units

Answer

The radius of disc is 16 units

Answer

The radius of disc is 32 units