Arccosine — Precalculus, what it means and where it is taught
The inverse of cosine, restricted to outputs from 0° to 180°.
Taught in Precalculus.
Where it is taught
What it rests on
Work through these first if this one does not settle.
- Cosine — cos θ = adjacenthypotenuse.
Practise this idea
1 question in the course bank use Arccosine, in Inverse Trigonometric Functions.
Problem 1
Find arccos(-12) in degrees.
Worked answer
120
Reference angle 60°
Cosine is negative in quadrant II, so 180-60=120