assessment 1

• The sine rule is used when we are given either two angles and one side, or two sides and a non-included angle
• The cosine rule is used when we are given either three sides or two sides and the included angle.
• angle = sinA/a = sinB/b = sinC/c
• side = a/sinA = b/sinB = c/sinC
• cosA = b2 + c2-a2 / 2bc (cosine rule)
• the angle at the centre of a circle is twice the angle at the circumference
• angles in the same segment are equal
• the angle in a semicircle is a right angle for 90 degrees
• opposite angles in a cyclic quadrilateral add up to 180 degrees

  
• alternate segment theorem

  
• tangents to a circle from an external point are equal in length

  
• a tangent to a circle is perpendicular (or 90 degrees) to the radius