# How do you evaluate using a calculator of #tan^-1(-1.7321)#?

##### 2 Answers

#### Explanation:

This question is asking "What angle(s) has a tan value of

**Step 1** . "In which quadrants is tan negative?"

From the **CAST** rule:

**Step 2** . Find the root angle. Find

This gives the acute angle in the 1st quadrant from which we can get the angles in the other quadrants.

**Step 3** Find the angles in the 2nd and 4th quadrants:

2nd quadrant:

4th quadrant:

CHECK: use a calculator to verify that:

These are the angles for

Method shown below.

#### Explanation:

You will have to do a hunt on your key pad.

Using my now very outdated Casio fx-9700GE

Shift then tan

Do not use the 'minus' key but use the 'negative' key. On my machine designated as

After using

After that I have to use the key marked 'EXE' . Yours may be labelled Ans

Whatever it is it is the one you would have to press make it solve something like 2+3