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# Online Tutorial -CG50: Using SolveN for Trig Equations

## Video Transcript

In this tutorial, we'll be looking at how to find all the roots of an equation which lie in a given interval. We'll be looking at the trig equation sin 2X = equals 0.5, looking for roots in the interval 0 to 2 Pi. You'll need to change the settings on your calculator to make sure it's working in Radians. To work along with this tutorial. You may find it best to reset your calculator first.

Choose run mode, go to setup and scroll down to angle type. Choose radians and execute. Press option and CALC. And then from this menu, select SolveN. Inside the bracket, type the equation. You must use the X Theta T key for X and shift decimal point for the equals. To complete the instructions, press comma, X Theta T, comma, zero comma and then 2 Pi. Close the brackets and then execute. A warning screen will remind you that there may be other roots of this equation which are outside the interval that you've chosen.

Exit gives you the roots of the equation as fractions of Pi. To change from fractions to decimals, you can press the SD key. Or you can move the cursor up to highlight the answers and press execute. This will give you a list of the answers. Move the curses down to see each root to more decimal places.

SolveN is a really useful check for trig equations that you might be asked to solve algebraically. But SolveN will also solve equations that cannot be solved algebraically. Explore using SolveN and see what else it can do.

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