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1. I need to find correct to 1dp the two smallest postive values of theta which satisfys sin theta= -0.84

so first of all i did inverse sin theta -0.84 = -57.1 then using the symmetry property sin(180-theta)=sin theta I did 180-(-57.1)=237.1 for the first then i did 360+57.1 to get 302.9

Also im ot too sure why for some questions such as the example given you use the supplimentary rule sin(180-theta)=sin theta

but for others such as cos theta =0.8 we use the oeriodic property cos(theta-360)=cos theta how can you tell what rnage it will be in?

You can always use the rules for sin(180-theta) etc but to determine which rule you want to use, always sketch a graph to help you decide which solutions to find.
3. use the cast system
4. Sketching the graph is the best way to start on any of these trig questions!

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Updated: December 14, 2010
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