In RS Aggarwal class 9 maths chapter 7 from Utopper, you will learn about a number of angles. At a zero angle, both sides of the angle are on the same plane and in the same place. After that, there is a sharp angle that isn't exactly 90 degrees but is more than 0 degrees and less than 90 degrees. This kind of angle can be seen in the slope of bridges where you drive your car. Then there is a 90-degree angle, also called a "right angle," which you can find in your home. The angle between your floor and the walls of your room is 90 degrees. Last, we have an obtuse angle, which is more than 90 degrees but less than 360 degrees. In shopping malls, you can find ramps, stairs, and escalators that are at an angle to the floor.