Spetsvinkel

Spetsvinkel is the Swedish term for an acute angle, a basic concept in Euclidean geometry. An acute angle measures greater than 0 degrees and less than 90 degrees (0° < θ < 90°), or in radians between 0 and π/2. It is strictly smaller than a right angle (90°) and smaller than an obtuse angle (greater than 90°).

Acute angles appear in many geometric constructions and classifications. A triangle whose three interior angles are all acute is called an acute triangle. Two angles that are acute can be complementary if their measures add up to 90 degrees. In standard notation an angle is often indicated by three letters, for example ∠ABC, or by a single letter at the vertex such as ∠A.

In trigonometry acute angles correspond to arguments in the first quadrant, where the primary trigonometric functions have well-defined positive values for sine, cosine and tangent. Acute angles are important in solving right triangles, where non-right angles are acute and relate to the legs and hypotenuse through sine, cosine and tangent ratios.

Practical applications include architecture and engineering design, navigation and surveying, computer graphics and robotics, where precise control of orientation and direction often requires understanding and using acute angles. The concept is fundamental and widely used across mathematics, science and applied fields.