1. Simple Trigonometric Equations The sine graph below illustrates that there are many solutions to the trigonometric equation sin x = 0.5.

2. When solving an equation such as sin x = 0.6, we can use a calculator.

3. Set your calculator in radian mode. This means that 0.6435 is the reference angle for other solutions. Since x is positive, and sine is positive in the first and second quadrants,  - 0.6435 is also a solution.

4. To solve an equation involving a single trigonometric function, we first transform the equation so that the function is alone on one side of the equals sign. This is the reference angle Cos is negative in the second quadrant so Cos is also negative in the third quadrant so

5. Inclination and Slope