SOLVING TRIG EQUATIONS www.mathsathawthorn.pbwiki.com SOLVING TRIG EQUATIONS Multiple Angles WJEC C2 January 2008

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.

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

FINAL SOLUTIONS