• 三角さんかく — triangle
• 角度かくど — angle / degree
• 直角ちょっかく — right angle
• 鋭角えいかく — acute angle
• 角膜かくまく — cornea
• 角質かくしつ — keratin / horny layer
• 角笛つのぶえ — horn (instrument)
• 角つの — horn (animal)

角 originally depicted an animal’s horn. From this physical shape, the meaning expanded to corners, angles, and sharp projections.

The readings reflect its range: つの for horns, かど for corners, and カク for abstract angles and measurements.