from a handpicked tutor in LIVE 1to1 classes
90 Degree Angle
A 90degree angle is a right angle. If the value of the angle between the horizontal and vertical lines is exactly equal to 90 degrees, then the angle is called a 90degree angle. Some of the reallife examples of a 90degree angle are the angle between the hands of a clock at 3 o'clock or 9 o'clock, angles between two adjacent edges of a rectangular door or window, etc.
1.  What is a 90 Degree Angle? 
2.  How to Draw 90 Degree Angle? 
3.  FAQs on 90 Degree Angle 
What is 90 Degree Angle?
A 90degree angle is a right angle and it is exactly half of a straight angle. It always corresponds to a quarter turn. Rectangle and square are the basic geometric shapes that have a measurement of all four angles as 90 degrees. When two lines intersect each other and the angle between them is 90 degrees then the lines are said to be perpendicular.
Look the image given below shows what a 90degree angle looks like. Angle DAB is a 90degree angle. It is formed by a ray AB with its perpendicular ray DA.
How to Draw 90 Degree Angle?
The 90degree angle can be drawn by using a protractor and compass.
Constructing 90Degree Angle Using a Protractor
Follow the given steps to construct a 90degree angle using a protractor:
 Step 1: Draw a ray OA.
 Step 2: Place the center of the protractor at point O.
 Step 3: In the outer or the inner circle of the protractor, look for 90° reading and with a pencil mark a dot and name it C.
 Step 4: Join O and C. You will observe the vertical line OC and horizontal line OA are perpendicular to each other and meeting at a common point O. Thus, ∠AOC = 90degree angle.
Constructing 90Degree Angle Using a Compass
Follow the given steps to construct a 90degree angle using a compass.
 Step 1: Draw a ray AB with help of a ruler.
 Step 2: Put the tip of the compass at A and draw an arc that cuts ray AB and mark that cut point as C.
 Step 3: Put the compass tip at C and draw an arc of radius AC that cuts the arc drawn in step 2 and mark that cut point as D.
 Step 4: With the compass tip at D, draw an arc of radius AC using a compass to cut the arc drawn in Step 2 and mark that cut point as E.
 Step 5: With the tip at D, draw another arc using the same radius AC between points D and E.
 Step 6: With the tip at E, draw another arc using the same radius AC to cut the arc drawn in step 5 and mark that cut point as F.
 Step 7: Join F and A. The angle FAB is a 90degree angle.
Important Notes:
 The 90degree angle is also called a right angle.
 A 90degree angle can be constructed with a protractor or a compass.
► Related Articles
Check out these interesting articles to learn more about the 90degree angle and its related topics.
90 Degree Angle Examples

Example 1: What fraction of a straight angle is a 90degree angle?
Solution: Straight angle is also a 180degree angle. Two 90 degree angles make one straight angle, as 2 × 90 degrees = 180 degrees. So, a 90degree angle is half a straight angle. Therefore, 1/2 of a straight angle is a 90degree angle.

Example 2: How many 90 degree angles are there in full rotation?
Solution: There are four 90 degree angles in full rotation.
A full rotation is equal to 360 degrees. Therefore, 360 degrees ÷ 90 degrees = 4.

Example 3: Each angle of the rectangle is a 90degree angle. Find the sum of all four angles of a rectangle.
Solution: Let the angles of a rectangle be A, B, C, and D in which let angle A = 90 degrees (given).
According to the property of the rectangle, all angles are equal and measures 90 degrees each.
Angles(A + B + C + D) = (90 + 90 + 90 + 90) = 360°.
Therefore, the sum of all four angles of a rectangle is 360 degrees.
FAQs on 90 Degree Angle
What are the Examples of a 90Degree Angle in Real Life?
In real life, we can see a 90degree angle in our surroundings such as the corners of a room, corners of a window, the screen of a mobile phone or laptop, etc. Each of the interior angles of any square or rectangle shape object is equal to 90 degrees.
How do you Define a 90 Degree Angle?
A 90degree angle is defined as the angle made by one horizontal line and one vertical line at a common point and the measurement of the angle between those two lines is exactly equal to 90 degrees.
Is a 90 Degree Angle Only RightAngle?
Yes, a 90degree angle is also known as a right angle. It can never be compared to an acute angle or an obtuse angle because any angle less than 90 degrees is an acute angle and greater than 90 degrees can be obtuse, straight, or a complete angle.
What is a 90 Degree Angle for Kids?
Kids can correlate the alphabet L with the 90degree angle. The 90degree angle is formed between the leg and arm of the alphabet L.
How Many 90 Degree Angles are there in a Triangle?
The triangle can have one 90 degree angle and two acute angles (angles less than 90 degrees). The sum of all the angles of a triangle is equal to 180 degrees. Therefore, only one angle can be 90 degrees. The triangle, having a 90degree angle, is known as a rightangled triangle.
How Many 90 Degree Angles are there in a Straight Angle?
There are two 90 degrees angles in a 180degree angle or straight angle. As the sum of two 90 degree angles is equal to 180 degrees, also the half of 180 degrees is 90 degrees. Thus twice 90degree angles are there in a straight angle.
Which Tool is Easy to Draw a 90 Degree Angle?
A protractor is a measuring instrument that can be used to draw a 90degree angle and can be used for measuring other angles as well. Apart from that, a compass can also be used to construct an angle of 90 degrees.
Does a Rectangle have a 90 Degree Angle?
A rectangle is a geometric shape with four sides and all its four interior angles are equal to 90 degrees each. Because according to the properties of a rectangle, all the angles are equal and measures 90 degrees.
Do All Squares have Four 90 Degree Angle?
According to the properties of the square, all sides are equal and all angles are equal. As the sum of all angles is equal to 360 degrees, therefore, each angle of the square is 360 degrees ÷ 4 = 90degree angle. Thus, all angles of a square are 90 degree angles.
visual curriculum