geometry

Question 1

cosine rule

Answer 1

a^2 = b^2 + c^2 - 2bcCosA

Question 2

sine rule

Answer 2

SinA/a = SinB/b

Question 3

area of a triangle

Answer 3

1/2 abSinC

Question 4

arc length

Answer 4

rθ

Question 5

sector area

Answer 5

1/2r^2θ

Question 6

segment area

Answer 6

1/2r^2(θ-Sinθ)

Question 7

alternate segment theorem

Answer 7

the angle that lies between a tangent and a chord is equal to the angle subtended by the same chord in the alternate segment

Question 8

angles at the centre theorem

Answer 8

the angle at the centre is twice the angle at the circumference

Question 9

angles in the same segment theorem

Answer 9

angles in the same segment are equal

Question 10

angles in a semi circle

Answer 10

the angle in a semi circle is 90 degrees

Question 11

chord of a circle

Answer 11

if the radius is perpendicular to a chord it bisects it (splits it in half)

Question 12

cyclic quadrilateral

Answer 12

the opposite angles in a cyclic quadrilateral equal 180 degrees

Question 13

tangents of a circle

Answer 13

the radius meets the tangent at 90 degrees
tangents which meet at the same point are equal in length