How do you write an equation for a circle with point (3, 4) lies on a circle whose centre is at (-1, 2)?
The standard form of the equation of a circle is
where (a ,b) are the coordinates of the centre and r, the radius.
We are given the centre but have to find the radius.
Since we are given a point on the circle then the distance from this point to the centre is the
To calculate the radius use the
# (x_1,y_1)" and " (x_2,y_2)" are 2 coordinate points"#
Here the 2 points are (3 ,4) and (-1 ,2)
#(x_1,y_1)=(3,4)" and " (x_2,y_2)=(-1,2)#
Substitute a = -1 , b = 2 and r
#=sqrt20#into the equation of the circle.
#rArr(x+1)^2+(y-2)^2=20" is the equation of the circle"#