Online Geometry: Area of a Parallelogram, Theorems and Problems - Table of Content Geometry Problem 854 Triangle, Parallel lines, Parallelogram, Areas, Similarity, Concurrent lines. Geometry Problem 771 Area of a Parallelogram, Star, Pentagon, Triangles. Geometry Problem 604 Area of a Parallelograms, Triangle, Trapezoid, Area. Problem 583. Quadrilateral, Diagonals, Circumcenters, Parallelogram, Octagon, Areas. Problem 489. Parallelogram, Triangle, Quadrilateral, Area. Problem 477. Parallelogram, Triangle, Quadrilateral, Area. Problem 473. Triangle, Parallel, Side, Parallelogram, Area, Similarity. Problem 472. Triangle, Parallel, Side, Parallelogram, Area, Similarity. Problem 471. Triangle, Parallel, Side, Concurrency, Area, Similarity. Problem 470. Triangle, Parallel, Side, Parallelogram, Area, Similarity. Proposed Problem 398. Parallelogram, Area, Similarity, Congruence. Proposed Problem 396. Square, Angle Trisectors, Congruence, Area. Proposed Problem 251. Parallelogram, sides, diagonals, squares, areas. Proposed Problem 177. Parallelogram with Midpoints, Triangles, Areas. Proposed Problem 169. Parallelogram, Interior and Exterior Points, Diagonals, Pentagon, Triangles, Areas Proposed Problem 168. Parallelogram, Diagonal, Triangles, Pentagon, Areas. Proposed Problem 167. Parallelogram, Diagonal, Triangles, Areas. Proposed Problem 166. Parallelogram, Diagonal, Triangles, Areas. Proposed Problem 165. Parallelogram, Diagonal, Triangles, Areas. Proposed Problem 164. Parallelogram, Trapezoid, Diagonal, Triangles, Areas. Proposed Problem 162. Parallelogram, Triangles, Areas. Proposed Problem 161. Parallelogram, Midpoints, Octagon, Areas. Proposed Problem 146. Varignon's Theorem: Quadrilateral, Midpoints, Parallelogram, Area, Perimeter. Varignon and Wittenbauer parallelograms. Quadrilateral: midpoints and trisection points of the edges, Area 1/2, 8/9.