C: Coordinate Geometry

Question 1

Equation of straight line

Answer 1

y - y1 = m (x - x1)

Question 2

Equation of circle

Answer 2

(x-a)^2 + (y-b)^2 = r^2
Centre = (a,b)
Radius = r

Question 3

Circle facts

Answer 3

• Angle in semicircle is 90°
• Perpendicular from centre to a chord bisects chord
• Radius is perpendicular to tangent at that point

Question 4

Parametric equations

Answer 4

dy/dx = dy/dt * dt/dx