Higher Mathematics
Videos created by K Oppo & N Lyons available via youtube channel:

Trigonometry
Video 1 – Solving basic trig equations

Video 2 – Solving quadratic trig equations

Video 3 – Solving trig equations in radians

Video 4 – Trig equations involving a double angle

Video 5 – Compound angles sine rule

Video 6 – Compound angles cosine rule