This course about 2D/3D Trigonometry is very useful and helpful.
Gary sir introduces many different useful formulas that can be used in a wide range of questions types.
Although some out-of-syllabus formulas are also taught, those formulas have proven to be quite useful and can solve certain questions in a shorter amount of time compared with the methods taught in school.
I would definitely recommend this course to anyone who is learning the 2D/3D Trigonometry topic!