Question

A circle is centered at the point (-7, -1) and passes through the point (8, 7).

The radius of the circle is ___ units. The point (-15, ___) lies on this circle. What are the answers?

Answer 1

Find Radius using distance formula.

`radius = √((8 -- 7)^2 +(7--1)^2) \\`

=
`√(15^2 + 8^2) = √(225 + 64 ) =√(289) = 17 units`

Since the point (-15, y) lies on the circle. The distance between (-7, -1) and

(-15, y ) will be 17 units.

So again using distance formula we will find y.

`radius = √((-7 --15)^2 + (-1-y)^2) \\\\17 = √(8^2 + (y+1)^2)\\\\squaring \ both \ sides \\\\289 = 64 + (y+1)^2\\\\289-64=(y+1)^2\\\\225 = (y+1)^2\\\\taking \ squaring \ root\\\\15 = y+1\\\\y=14`

point (-15, 14)