What is an angle? What angles are called acute, straight, obtuse, unfolded?

An angle is a geometric figure formed by two rays (sides of an angle) emanating from one point (which is called the vertex of the angle).
Flat angle is an angle whose degree is 180 degrees.
A right angle is called an angle of 90 degrees.
Obtuse is an angle of a degree grid which is greater than 90 degrees, but less than 180 degrees.
An acute angle is an angle whose degree grid is less than 90 degrees.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.