When visiting a new city or place, it would help to know the directions to guide us around. A map can be very useful. It lets us know where we are and can also help us identify directions that will help in navigating through a city. 

The opposite edges of a desktop screen are always equally spaced and do not meet.
They are thus, examples of parallel lines.

A 90-degree angle is also called a right angle.

A straight angle measures 180°.
A reflex angle measures more than a straight angle of 180°, but less than a full circle of 360°.
Hence, a straight angle is less than a reflex angle.

• An angle which measures ${360}^{\circ }$ is  called a whole angle.


• An angle which meaures greater than ${180}^{\circ }$ and less than ${270}^{\circ }$ is called an obtuse angle.


• An angle which measures ${180}^{\circ }$ is called a straight angle. 


• An angle which measures ${90}^{\circ }$ is called a right angle. 

When two (or more) lines are always at the same distance from each other and never intersect each other, they are called parallel lines.
The railway lines are examples of parallel lines.

A right angle is equal to 90 degrees. 
A straight angle is equal to 180 degrees.
$90\times 2=180$
Hence, two right angles make a straight angle.

$\begin{array}{cc}\text{Type of angle}& \text{Description}\\ \text{Acute angle}& \text{Less than}{90}^{\circ }\\ \text{Right angle}& \text{Equal to}{90}^{\circ }\\ \text{Obtuse angle}& \text{Greater than}{90}^{\circ }\\ & \text{\& less than}{180}^{\circ }\\ \text{Straight angle}& \text{Equal to}{180}^{\circ }\end{array}$
Thus, an angle that measures less than ${180}^{\circ }$ and greater than ${90}^{\circ }$ is called an obtuse angle.

The angle shown in the figure is more than a straight angle of 180 degrees and less than a full circle of 360 degrees.
Hence, it is a reflex angle.

An angle that is less than 90${}^{\circ }$ is called an acute angle.
Hence, 35${}^{\circ }$ and 88${}^{\circ }$ are less than ${90}^{\circ }$.
So, both acute angles.