Learn and revise trigonometric ratios of sine, cosine and tangent and calculate angles and lengths in right-angled triangles with GCSE Bitesize AQA Maths.

Show that the tangent lines to the graph of x2−xy+y2 = 3, x 2 − x y + y 2 = 3, at the points where the graph crosses the x x -axis, are parallel to each other.