Question

If the angle is greater than $0^0$and less than ${90}^0$ , then the angle is known as:
A. Obtuse angle
B. Right angle
C. Acute angle
D. Reflex angle

Answer 1

Hint: The classification of angles is to be used to determine the type of angle in the given range in degrees.

Complete step-by-step answer:

In the given problem, it is asked what is the angle known as if the angle is greater than $0^0$ and less than ${90}^0$.

In plane geometry, an angle is the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle.

There are two commonly used units of measurement for angles.

The more familiar unit of measurement is that of degrees. A circle is divided into ${360}^0$ equal degrees.
The other one is radians. It can be represented on a real number line. It follows ${360}^0=2\pi$ radians.

Angles are classified into four types in the basis of range of their value measures in degree or radian.
These are:
Acute angle: An angle that lies between $0^0$ and ${90}^0$.
Obtuse angle: An angle that lies between ${90}^0$ and ${180}^0$.
Reflex angle: An angle that lies between ${180}^0$ and ${360}^0$.
Right angle: An angle that is equal to ${90}^0$.

From the above classification, it is clear that if the angle is greater than $0^0$ and less than ${90}^0$ , then the angle is known as acute angle.

Hence option (C). Acute angle is the correct answer.

Note: The angles greater than ${360}^0$ can also be represented as starting from $0^0$. Angle equal to ${180}^0$ can be called as a straight angle and an angle equal to ${360}^0$ can be called as a complete angle. Angles having common vertex and a common ray are known as adjacent angles.