This introduction covers The Special Triangles within Exact Trig Values for GCSE Mathematics. Revise Exact Trig Values in Geometry & Measures for GCSE Mathematics with 14 exam-style questions and 4 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 1 of 7 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.
The Special Triangles
For certain angles, trig values can be written exactly using surds and fractions - no decimals needed! These come from two special triangles: the 45-45-90 isosceles and the 30-60-90 from splitting an equilateral. Learn the pattern - you WILL need these!
Practice questions for Exact Trig Values
What is the exact value of sin 30°?
James says that sin 30° and cos 60° are equal. Is James correct? Explain your answer using exact values.
Quick recall flashcards
Sin Pattern
sin 0°=0, sin 30°=1/2, sin 45°=√2/2, sin 60°=√3/2, sin 90°=1. Pattern: √n/2 for n=0,1,2,3,4
Cos Pattern
Cos is sin BACKWARDS. cos θ = sin(90°-θ). So cos 30° = sin 60°, etc.