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

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)

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

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) = n or = π/6 + 2πn

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.