U2 Trigonometry(KA/PRE/U2)
Unit 2: Trigonometry
Special Trigonometric Values in the First Quadrant
In the first quadrant (0° to 90°), sine, cosine, and tangent are all positive. Key angles: 30°, 45°, 60°.
Trigonometric Identities on the Unit Circle
The unit circle shows that sin²θ + cos²θ = 1 for all angles θ.
Inverse Trigonometric Functions
Inverse functions (like sin⁻¹x) return angles based on given trigonometric ratios.
Law of Sines & Law of Cosines
Law of Sines: a/sin(A) = b/sin(B) = c/sin(C)
Law of Cosines: c² = a² + b² - 2ab·cos(C)
Solving General Triangles
Use Law of Sines or Law of Cosines to solve any triangle (not just right triangles).
Sinusoidal Equations & Models
Real-world periodic phenomena (sound waves, tides, seasons) are modeled with sine and cosine functions.
Angle Addition Identities
Example: sin(A+B) = sinA·cosB + cosA·sinB
Using Trigonometric Identities
Identities simplify complex expressions and solve equations involving trigonometric functions.
Quiz: Test Your Understanding
Which of the following is always true for any angle θ?
- sin(θ) + cos(θ) = 1
- sin²(θ) + cos²(θ) = 1
- tan(θ) = sin(θ) + cos(θ)
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