Math: solutions to sin equations

Tutoring math, you see trig equations. The tutor mentions some top-down ideas.

Considering the equation

sinx=K, for K ε Reals

sinx = sin(180°-x), 0≤x<90°. Therefore, if the equation has a solution θ between 0 and 90°, it will typically have another at 180° – θ.

Between 180° and 360°, a similar idea applies: sin(180°+γ) = sin(360°-γ), 0≤γ<90°.

These ideas can help when trying to find the second solution to a sin equation.

Source:

Travers, Kenneth et al. Using Advanced Algebra. Toronto: Doubleday Canada Limited, 1977.