Adjacent angles are one of the earliest and most important concepts to learn in basic geometry, as they have applications in further subjects like trigonometry, physics, and engineering.

The cosine (cos) function takes the angle Ɵ and gives the answer to adjacent ÷ hypotenuse (in this example, 16/32). cos⁻¹ is the inverse function of cos. The cos⁻¹ function takes the ...