SME
Grade 12 Math
Sum, difference and double-angle formulas; trigonometric equations
The main lesson, then each kind of problem it solves.
Sum, difference and double-angle formulas; trigonometric equations
Main lesson
The difference formula for cosine
Use this for “Find the exact value of cos 15° as cos(45° − 30°).”
Double-angle formulas
Use this for “sin A = 3/5 with A in Quadrant II. Find sin 2A and cos 2A.”
Half-angle formulas
Use this for “cos A = 7/25 and A/2 is in Quadrant I. Find sin(A/2) and cos(A/2).”
Solve a sin x + b = c
Use this for “Solve 2 sin x + 3 = 4 for 0° ≤ x < 360°.”
Solve a tan x + b = c
Use this for “Solve 3 tan x + 1 = 4 for 0° ≤ x < 360°.”
A quadratic in sin x
Use this for “Solve 2 sin²x − sin x − 1 = 0 for 0° ≤ x < 360°.”