Start with the right-angled triangle
Start with the right-angled triangle

A right-angled triangle has one angle of 90∘90^\circ90∘, usually shown by a small square. The longest side, opposite the right angle, is always the hypotenuse.
Step-by-step lessons on Edexcel IGCSE Maths SOHCAHTOA (Trigonometry). Each one builds up to exam-style questions. Build confidence with the shared Foundation-tier content first, since roughly 40% of Higher-tier marks are targeted at the grades 4–5 boundary that both tiers have in common.