M - Pure 1 - 10) Trigonometric identities and equations

Question 1

Explain a CAST diagram

Answer 1

Out of sin, cos and tan:

• TR → All positive
• TL → Sin positive
• BR → Tan positive
• BL → Cos positive

Question 2

List the trigonometric equations

Answer 2

• sin²(θ) + cos²(θ) ≡ 1
• sin²(θ) ≡ 1 - cos²(θ) ·and· cos²(θ) ≡ 1 - sin²(θ)
• tan(θ) ≡ sin(θ) / cos(θ)

Question 3

Method to find trigonometric values which are like sin(3θ + 60°)

Answer 3

1. Adjust both lower and upper bounds of the angle interval (e.g. ×3 +60)
2. Find all values within that new interval
3. Adjust all those values (e.g. -60 ÷3)