- Right angle (Wikipedia)
In geometry and trigonometry, a right angle is an angle of exactly 90 degrees or 𝜋/2 radians corresponding to a quarter turn. If a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles. The term is a calque of Latin angulus rectus; here rectus means “upright”, referring to the vertical perpendicular to a horizontal base line.
- Aldebaran (Wikipedia)
Aldebaran (Arabic: الدَّبَران, lit. ‘The Follower’) is a star located in the zodiac constellation of Taurus. It has the Bayer designation α Tauri, which is Latinized to Alpha Tauri and abbreviated Alpha Tau or α Tau. Aldebaran varies in brightness from an apparent visual magnitude 0.75 down to 0.95, making it the brightest star in the constellation, as well as (typically) the fourteenth-brightest star in the night sky. It is positioned at a distance of approximately 65 light-years from the Sun. The star lies along the line of sight to the nearby Hyades cluster.
