This semicircular protractor is housed in its original wooden fitted case. The case is in very poor condition, but it was originally covered with thin leather and lined with purple velvet. The case is ...

Angles are often described using three letters. Angles can be drawn and measured using a protractor. Finding angles between lines Complementary angles form a right angle. Supplementary angles form a ...

This brass circular protractor was manufactured in the mid-19th century and made available for sale by the New York City firm headed by Benjamin Pike (1777–1863). Pike, a dealer of optical, ...