I'm talking about trigonometry, of course: that bastion of angles and triangles that is essential to calculating velocity, momentum, and much more.

To decide whether the two triangles are similar, calculate the missing angles. Remember angles in a triangle add up to 180°. Angle yxz = 180 85 40 = 55 ∘ Angle YZX = 180 85 55 = 40 ∘ Answer ...

Learn about congruent and similar shapes with this BBC Bitesize Maths article. For students between the ages of 11 and 14.