1. SOLVING TRIG EQUATIONS
SOLVING TRIG EQUATIONS
Multiple Angles
WJEC C2 January 2008

2. First step is to adjust the interval to be consistent with the Angle (3x+15)
Next step is to find the INVERSE SIN of 0.5. This is sometimes called ARCSIN
And is written
Note that this is not a solution
But is the PRINCIPAL VALUE
of 3x+15.
The PRINCIPAL VALUE is the Angle which is in the FIRST QUADRANT
That means the Angle which is between 0 and 90 degrees.

3. Now we solve for x NOW use the CAST diagram
(or you can use the Graph of sin A)
to identify the other solutions for 3x+15
180
270 90 30 A S T C
Don’t forget we are looking for
solutions for 3x+15 up to 555 degrees!
Now we solve for x

4. FINAL SOLUTIONS