Question

2. Given the equation of a circle in standard form, identify the center, radius, and graph the circle.

Answer 1

Answer:

Center: ( -1 , 2 )

Radius: 6

Step-by-step explanation:

The equation for a circle is given as follow:

$(x-h)^{2} +(y-k)^{2} =r^{2}$

Where,

the Center is: ( h , k ) (note that the signs of the number are different)

and the radius is: r

So if we compare the original circle equation to the equation in the question we can see that:

$(x+1)^{2} +(y-2)^{2} =36$

the Center is: (-1,2)

and the radius is: $\sqrt{36}$ = 6

2. To draw the graph find points that lay on the circle, it's better to take the values of x and y from the Center:

first sub y=2 in the equation to find the values for x:

$(x+1)^{2} +(y-2)^{2} =36$

$(x+1)^{2} +(2-2)^{2} =36$

$(x+1)^{2} +(0)^{2} =36$

$(x+1)^{2} =36$

$x+1 =±\sqrt{36}$

$x=6-1$    AND    $x=-6-1$

$x=5$          AND    $x=-7$

• The points are A(5,2)  and  B(-7,2)

second sub x= -1 in the equation to find the values for y:

$(x+1)^{2} +(y-2)^{2} =36$

$(-1+1)^{2} +(y-2)^{2} =36$

$(0)^{2} +(y-2)^{2} =36$

$(y-2)^{2} =36$

$y-2=±\sqrt{36}$

$y=6+2$    AND    $y=-6+2$

$y=8$          AND    $y=-4$

• The points are D(-1,8)  and  E(-1,-4)      

After finding the points write them in the graph and match them together to get the like the circle in the picture below: