as well as the challenges of angular watch design and the future of square and rectangular timepieces. Mr. Palmgren’s email said he wrote the book, with some research help from Christie’s ...

Quadrilaterals are 2D shapes with four sides and angles. There are six special quadrilaterals with different properties. A rectangle has two pairs of equal sides. It has four right angles (90°).

The dashes on the lines show they are equal in length. All of the angles are also equal. A right-angled triangle is a triangle that has a right angle. The angles inside a shape are called interior ...