Robert Link@futurebird @Infrapink @jacquiharper A tangent is a straight line?
https://mathbooks.unl.edu/PreCalculus/tangent-and-cofunctions.html
GNU social JP is a social network, courtesy of GNU social JP管理人. It runs on GNU social, version 2.0.2-dev, available under the GNU Affero General Public License.
All GNU social JP content and data are available under the Creative Commons Attribution 3.0 license.