6. circles Flashcards
1
Q
midpoint of 2 coordinates equations
A
(x1+x2/2 , y1+y2/2)
2
Q
equation of a circle with centre (0,0) and radius r
A
x^2 + y^2 = r^2
3
Q
equation of a circle with a centre (a,b) and radius r
A
(x - a)^2 + (y - b)^2 = r^2
4
Q
one point of intersection
A
touches the circle once
5
Q
two points of intersections
A
goes through the circle twice
6
Q
no point of intersection
A
does not touch the circle at all
7
Q
tangent to a circle is
A
perpendicular to the radius of the circle at point of intersection
8
Q
perpendicular bisector of a chord
A
will go though the centre of a circle
9
Q
angle in a semi circle is always a
A
right angle
90 degrees
