Fixed documentation of IfcSineSpiral and IfcCosineSpiral

docs/schemas/resource/IfcGeometryResource/Entities/IfcCosineSpiral.md

@@ -1,16 +1,24 @@
 # IfcCosineSpiral
 
-A type of spiral curve for which the curvature change is dependent on the cosine function.
+*IfcCosineSpiral* is a type of spiral curve for which the curvature change is dependent on the cosine function.
 <!-- end of short definition -->
+The cosine spiral curve is parameterized by its curve length and for a given parameter $s$, the heading angle $\theta(s)$ and the curvature $\kappa(s)$ are defined as follows. Here, $A_0$ corresponds to the *ConstantTerm* and $A_1$ to the *CosineTerm*.
 
-The curvature is defined as:
+**Heading Angle:**
 
-K = K0/2 (Constant - cos&pi s/CosineTerm)
+The *Heading Angle* $\theta(s)$ represents the orientation of the tangent to the curve at a given arc length. It indicates the direction in which the curve is "pointing" at that point. As you move along the curve, $\theta(s)$ changes, showing how the curve’s direction evolves.
+
+$$\theta(s) = \frac{1}{A_0} s \;+\; \frac{L}{\pi A_1} \sin\!\biggl(\frac{\pi}{L}s\biggr)$$
+
+**Curvature:**
+
+The *Curvature* $\kappa(s)$ describes how quickly the heading angle changes with respect to the arc length $s$. It reflects the "tightness" of the curve. Higher curvature values correspond to sharper bends, and lower curvature values correspond to straighter segments.
+
+$$\kappa(s) = \frac{L}{A_0} \;+\; \frac{L}{A_1}\cos\!\biggl(\frac{\pi}{L}s\biggr)$$
 
 ## Attributes
 
 ### CosineTerm
 
-
 ### ConstantTerm
 

docs/schemas/resource/IfcGeometryResource/Entities/IfcSineSpiral.md

@@ -1,19 +1,26 @@
 # IfcSineSpiral
 
-A type of spiral curve for which the curvature change is dependent on the sine function. It is also known as the Klein curve.
+*IfcSineSpiral* is a type of spiral curve for which the curvature change is dependent on the sine function.
 <!-- end of short definition -->
+The sine spiral curve is parameterized by its curve length and for a given parameter $s$, the heading angle $\theta(s)$ and the curvature $\kappa(s)$ are defined as follows. Here, $A_0$ corresponds to the *ConstantTerm*, $A_1$ to the *LinearTerm*, and $A_2$ to the *SineTerm*.
 
-The curvature is defined as:
+**Heading Angle:**
 
-K = K0 (s LinearTerm - 1/2&pi sin2&pi/SineTerm)
+The *Heading Angle* $\theta(s)$ represents the orientation of the tangent to the curve at a given arc length. It indicates the direction in which the curve is "pointing" at that point. By following changes in $\theta(s)$ along the curve, one can understand how the curve rotates and changes direction as it progresses.
 
-## Attributes
 
-### SineTerm
+$$\theta(s) = \frac{1}{A_0} s \;+\; \frac{1}{2}\left(\frac{A_1}{|A_1|}\right)\left(\frac{s}{|A_1|}\right)^2\;-\; \frac{L}{2\pi A_2}\biggl(\cos\bigl(\frac{2\pi}{L}s\bigr)-1\biggr)$$
 
+**Curvature:**
 
-### LinearTerm
+The *Curvature* $\kappa(s)$ describes how quickly the heading angle changes with respect to the arc length. In other words, curvature indicates how "tight" a curve is turning at any point. A larger curvature corresponds to a sharper bend, while a smaller curvature corresponds to a straighter segment of the curve.
 
+$$  \kappa(s) = \frac{L}{A_0} \;+\; \frac{A_1}{|A_1|}\left(\frac{L}{|A_1|}\right)^2  \frac{s}{L} \;+\; \frac{L}{A_2}\sin\left(\frac{2\pi}{L}s\right) $$
+
+## Attributes
 
-### ConstantTerm
+### SineTerm
+
+### LinearTerm
 
+### ConstantTerm