Lawrence's blog

the concept i will go over is from section 8-1

you are solving for theta. for you to get theta you have to get the trig function by itself and then you have to take the inverse.

inverses have 2 answers. first you must find where the angle is based on the trig function, and then find out if it is positive or negative.

Step: take the inverse of the positive number.

these are the steps to get from the first quadrant to the other three quadrants.

Q2: make the number negative and add 180 degrees

Q3: add 180 degrees

Q4: make the number negative and add 360 degrees

ex. 5sec theta+6=0

now you must subtract 6 to get:
5 sec theta= -6

you arent close to being done yet. now you divide by 5
sec theta= -6/5

now you have to take the inverse which gives you:
theta=sec-1 (6/5)

you have to convert it to the inverse of cos because there isnt a secent inverse on the calculator. so now you have:
theta=cos-1 (5/6)= 33.557 this is in Q1

now you have to find where X is negative. X is negative in Q2 and Q3

to get it in Q2: make 33.557 negative and then add 180 degrees
theta= -33.557 +180= 146.443 (first answer)

now you have to get it in Q3. you just add 180 degrees
theta= 33.557+180= 213.557 (second answer)

now you are done. you just completed the problem and got it right!

that is what i learned from section 8-1. i think its really easy. its just like chapter 7, where you have to know your formulas inorder for you to pass.