Solving Trig Equations

Finding every solution

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Trig equations have many solutions. Use symmetry: $\sin(\pi - x) = \sin x$.
• Add multiples of $2\pi$ for every solution.
• Factor rather than dividing, so no solutions are lost.

Steps

1. More than one answer
2. Count the solutions
3. Find another solution
4. Use an identity
5. Going round again
6. A quadratic in disguise