This study notes covers Worked Example 2 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 5 of 7 in this topic. Use this study notes to connect the idea to the wider topic before moving on to questions and flashcards.
Worked Example 2
Find the exact value of 2 sin 45° cos 45°.
Solution
From the exact values table:
sin 45° = √2/2
cos 45° = √2/2
2 sin 45° cos 45° = 2 × (√2/2) × (√2/2)
= 2 × (√2 × √2)/(2 × 2)
= 2 × 2/4
= 4/4 = 1
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.