Question

How do you evaluate `Tan^-1(2.8/4)`?

Answer 1

`arctan 0.7 = 35.0°`

Explanation:

The question is asking for the size of the angle which will have the length of the opposite side as 2.8 and the adjacent side 4.
`tan^(-1)` is called arctan and must not be confused with `1/(tan theta)` which is called `cot theta`

This can only be done by using a calculator or from tables.
On a calculator use the shift/alt/2nd function key and the `tan^(-1)` key

`2.8 div 4 = 0.7`

`arctan 0.7 = 35.0°`

This is another way of saying that in a right-angled triangle with an angle of 35.0°, the opposite side will be 70% of the length of the adjacent side.