2. What do they do? These are the way we can undo a trig function Just like we subtract to undo adding Divide to undo multiplication Take the root to undo an exponent Raise by the base to undo a log

3. What do they look like? These are the shift/2 nd /function buttons on the sin/cos/tan buttons sin -1 (y/r) = angle cos -1 (x/r) = angle tan -1 (y/x) = angle So you input the ratio, and it outputs an angle (unlike the sin(), cos(), and tan(), where you input angles and they output ratios)

4. Let’s use them then sin -1 (1/2) = angle cos -1 (1) = angle tan -1 (1) = angle sin -1 (√(3)/2) = angle cos -1 (- √(3)/2) = angle tan -1 (0) = angle

5. How to write the answer As you hopefully noticed in doing the examples, these inverse functions get more than one answer So, we write the answer in a way to account for that, using +360n or +2πn for sin or cos, and +180n or + πn EG: sin -1 (1/2) = 30 + 360n or = π/6 + 2πn

6. What if it’s csc, sec, cot? Solve for the ratio; for csc, for example, set the thing in parenthesis equal to the ratio r/y; since r is always 1, you can solve easily by cross multiplication.