Peaucellier's linkage allows to transform a rotary-motion into a straight-line motion. The invention that appeared in 1864, was important for the development of steam engine.
Area under the Curve
Area of a Circle - Wedge/Sector Demonstration
Matching sin graphs
Transformations of Parabolas
Exploration 1 - Proportionallity with Angle Bisector
Reflect Points X Axis
Vector Field 3D