Circle Theorem - Term 1 Flashcards
What does a tangent do?
A tangent touches the edge of the circle at one point
What is the rule for tangents and a radius?
A tangent and a radius meet to make 90*
What is the rule for tangents on an extended point?
Tangents from an extended point to a circle are equal in length
What is the rule for angles on an arrowhead shape?
The angle at the centre is twice the size of the angle at the circumference
When does the angles on an arrowhead rule apply?
An angle must be in the centre and the other three are touching the circumference of the circle
What is the rule for angles in a segment? (Bowtie shape)
Angles in the same segment are equal
When does the angles on a (segment) bowtie rule apply?
All points must be touching the circumference
What is the rule for one angle in a triangle in a semicircle?
The angle in a semicircle is always 90*
What do we look for in angles in a semicircle?
One length of the triangle must go through the centre of the circle. All vertices are touching the circumference
What is the rule for angles in a cyclic quadrilateral?
Opposite sides in a cyclic quadrilateral add up to 180*
What do you look for to identify a cyclic quadrilateral?
All points of the quadrilateral must be touching the circumference
What are the two rules of bearings?
Measured clockwise from north
Must always have 3 digits
I calculate that the bearing of point A to point B is 70*. How do I write this as a bearing?
070* because bearings must always have three digits
