Math Surprise Test (Circle Theroms)

1A

line from centre ⟂ to chord

1B

perp bisector of chord (if ⟂ and = then O is center)

2

∠ at centre = 2 × ∠ at circumference.

3

∠ in a semi-circle

CONVERSE 3

Chord subtends 90 (if 90 then diameter)

4

∠’s in the same segment

CONVERSE 4

Line subtends equal (if =∠ then cyclic quad)

IF equal chords; equal ∠’s (3)

THEN equal circles; equal chords; equal ∠’s

5

of cyclic quad (= 180)

CONVERSE 5

Opp ∠’s quad suppl (if both equal 180)

6

Ext ∠ of cyclic quad

CONVERSE 6

Ext ∠ = int opp ∠

7

Tan ⟂ radius

CONVERSE 7

Line ⟂ radius (if ⟂ then tangent)

8

Tans from same pt

9

Tan chord theorem

CONVERSE 9

∠ between line and chord (if ∠=∠ then tangent line)