In the context of special right triangles, what is the name given to an angle that measures $90°$?

• A. Straight angle
• B. Acute angle
• C. Obtuse angle
• D. Right angle

Answer: (D)

Verified step by step guidance

1. Understand the definition of different types of angles based on their measures.
2. Recall that an angle measuring exactly 90 degrees is called a 'Right angle'.
3. Recognize that a 'Straight angle' measures 180 degrees, an 'Acute angle' measures less than 90 degrees, and an 'Obtuse angle' measures more than 90 degrees but less than 180 degrees.
4. In the context of special right triangles, the angle measuring 90 degrees is specifically referred to as the 'Right angle'.
5. Therefore, the angle measuring 90 degrees in special right triangles is called a 'Right angle'.