7-6

I'm going to teach you to solve for ø. The steps are different than an algebra equation.

1. Isolate the trig function.

2. Take the inverse of the trig function (arc sin)sin–1 (arc cos)cos -1

3. Use the trig chart or calculator to find answer (only use positive value)

4. Use quadrants to find the right angle. Positive or negative with trig function.

There are at least two answers for each inverse.

To move quadrants:

• Q1àQ2 make negative add 180º
• Q1àQ3 Add 180º
• Q1àQ4 Make negative add 360º

Now I'm going to show you an example using the steps above.

Cos^-1 (.2)

1. The trig function is already isolated.

2. The inverse is already taken.

3. Since .2 is not on the trig chart, you have to change it into degrees. You would then get 11.46. This means that it is in the quadrant I.

4. Because Cos is x/r, it would be in quadrants I and III. Since we already know the degree in Quadrant I is 11.46 we have to find the degree in quadrant III, to do that you would at 180º. so 11.46º+180º=196.46º. Now we have to change the degree into degrees, minutes and seconds.We learned this in the first section. So for 11.46, you would get 11º27'36" and 196.46º would be 196º27'36".

Your final answer would be Cos^-1 (.2)=11º27'36" and 196º27'36"

-----Carley Lynn Guidry-----