Crows in a lab were able to distinguish shapes that exhibited right angles, parallel lines, and symmetry, suggesting that, like humans, they have a special ability to perceive geometric regularity.

3rd level Finding angles between lines Angles made by parallel lines Complementary angles form a right angle. Supplementary angles form a straight line.

In flat space, two parallel lines never meet, however, they appear to meet at very distances for the same reason due to which objects appear smaller when they are at a distance than when they are ...

Geometry and measure Angles, lines and polygons - Edexcel Polygons are multi-sided shapes with different properties. Shapes have symmetrical properties and some can tessellate.

Horizontal lines run left to right, parallel to the horizon, with slope 0 and equation y = k. Vertical lines run top to bottom, perpendicular to the horizon, with undefined slope and equation x = k.

Damon Diemente, Algebra in the Service of Geometry: Can Euler's Line Be Parallel to a Side of a Triangle?, The Mathematics Teacher, Vol. 93, No. 5 (May 2000), pp. 428-431 ...