Complete Angle: Definition, Formation, Examples, Facts, FAQs

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What Is a Complete Angle in Math?

A complete angle is an angle that measures $360^{\circ}$. It represents a complete turn or full rotation and thus forms a circle around a point. A complete angle is also called a full angle, a round angle, or a perigon.

Visual of a Complete Angle

We know that if two rays meet at a common point (vertex), then an angle is formed. It is measured in units like “degrees” or “radians.” 

Angle in math

If the amount of turn around a point is equal to 360 degrees then the angle formed is a complete angle. Hence, a complete angle in math is a type of angle with a $360^{\circ}$ measurement. 

Complete angle in math

Definition of a Complete Angle

The complete angle is the angle formed when the incident or initial ray and the final ray coincide after a complete rotation or 360 degrees rotation. 

One 360 degrees rotation is equivalent to $2\pi$ radians. 

Complete angle

Formation of Complete Angle

A complete angle or a $360^{\circ}$ angle is formed when a ray completes a full rotation. It is the angle made by a ray to reach its final position from its initial position in a full rotation.

Let’s consider two rays, OA and OB. 

Complete angle between two lines

If OB takes a full turn and comes back to its original position, the angle between the two rays is the complete angle. 

$\angle AOB = 360^{\circ}$

Complete angle by a line

A complete angle is 6 times a $60^{\circ}$ angle, 4 times a right angle, and 2 times a straight angle.

A complete angle measures 360°

Construction of Complete Angle

How can we draw a complete angle? We can easily construct a complete angle using a protractor or a compass.

Construction of a Complete Angle using a Protractor

The 360-degrees-protractor can be used to draw a complete angle easily. It is round in shape. 

Construction of a complete angle using protractor

Construction of a Complete Angle Using Compass

To draw a complete angle using a compass, first draw a ray PQ. Put the pointer of the compass on the endpoint P and take a suitable width on the compass. Put the pencil tip on the ray PQ and draw a complete circle such that it meets the initial point in the end.

Construction of a complete angle using compass

Complete Angles Around Us

Let’s take a look at a few examples of a complete angle in real life.

Real-life examples of complete angles

Facts about Complete Angles

  • Wall clocks use the concept of full angles to show time.
  • Four right angles or two straight angles make one complete angle.
  • “Angulus” is the Latin word from which the word angle is derived. It means ‘corner.’

Conclusion

In this article, we learned about the complete angle, its real life applications, formation, and representation. Let’s now look at some solved examples and do some practice problems to understand the concept better.

Solved Examples on Complete Angle

  1. Check whether the pair of angles given below add up to a complete angle or not.

            (i) $170^{\circ},\; 180^{\circ}$       (ii) $115^{\circ},\; 244^{\circ}$    (iii)$120^{\circ},\; 240^{\circ}$

Solution:

A complete angle is equal to $360^{\circ}$

 (i) $170^{\circ},\; 180^{\circ}$

Sum of angles $= 170^{\circ} + 180^{\circ} = 350^{\circ} \neq 360^{\circ}$

Therefore, the pair $(170^{\circ},\; 180^{\circ})$ does not make a complete angle.

 (ii) $115^{\circ},\; 244^{\circ}$  

Sum of angles $= 115^{\circ} + 244^{\circ} = 359^{\circ} \neq 360$

Therefore, the pair $(115^{\circ},\; 244^{\circ})$  does not make a complete angle.

(iii) $120^{\circ},\; 240^{\circ}$

Sum of angles $= 120^{\circ} + 240^{\circ} = 360^{\circ}$

Therefore, the pair $(120^{\circ},\; 240^{\circ})$ makes a complete angle when added.

  1. Jane runs around a circular park in the morning from point A to point A. What kind of angle does her path make at the center? What does the distance covered by her in 1 round around the circular park represent?
Girl running on a circular path around a park

Solution:

Jane completes an entire round around a circular park from point A and ending at the same point. So, her path makes a full circle.

The angle made around the center of a circle is 360 degrees.

Thus, Jane’s path represents a complete angle at the center. 

Also, the distance covered by her in 1 round represents the circumference of the circle.

  1. In the figure given below, find the relation between the angles “a” and “b.”
Complete angle example

Solution:

As we know, the sum of angles around a point $=$ Complete angle $= 360^{\circ}$

So, $135^{\circ} + 65^{\circ} + a + b = 360^{\circ}$

$200^{\circ} +  a + b = 360^{\circ}$

$a + b = 360^{\circ} \;–\; 200^{\circ}$

$a + b = 160^{\circ}

Hence, the relation between “a” and “b” is $a + b = 160^{\circ}$.

  1. In the figure given below, calculate the value of “x.”
Example on complete angle

Solution:

As we know, the sum of angles around a point $= 360^{\circ}$

So, $108^{\circ} + 85^{\circ} + 60^{\circ} + x = 360^{\circ}$

$253^{\circ} + x = 360^{\circ}$

$y = 360^{\circ} \;–\; 253^{\circ} = 107^{\circ}$

Hence, the value of x is $107^{\circ}$.

  1. If three angles made at the center of a circle are $145^{\circ},\; 90^{\circ}$, and y. Find the value of y.

Solution:

Given angles made at the center of a circle: $145^{\circ},\; 90^{\circ}$, and y.

As we know, the sum of angles at a point $= 360^{\circ}$

So, $145^{\circ} + 90^{\circ} + y = 360^{\circ}$

$235^{\circ} + y = 360^{\circ}$

$y = 360^{\circ} \;–\; 235^{\circ} = 125^{\circ}$

Hence, the value of x is $150^{\circ}$.

Practice Problems on Complete Angle

Complete Angle: Definition, Formation, Examples, Facts, FAQs

Attend this quiz & Test your knowledge.

1

The sum of all angles around a point equals _____.

$360^{\circ}$
$270^{\circ}$
$180^{\circ}$
$90^{\circ}$
CorrectIncorrect
Correct answer is: $360^{\circ}$
The sum of all angles around a point equals $360^{\circ}$.
2

What is the ratio of a right angle to a complete angle?

1 : 2
1 : 3
1 : 4
2 : 3
CorrectIncorrect
Correct answer is: 1 : 4
The ratio of a right angle to a complete angle $= 90^{\circ} : 360^{\circ} = 1: 4$
3

A full rotation angle can be divided into how many straight angles?

2
3
4
6
CorrectIncorrect
Correct answer is: 2
A straight angle measures $180^{\circ}$. So, two straight angles add up to $360^{\circ}$. Hence A full rotation angle can be divided into two straight angles.
4

In which system is a complete angle represented as $360^{\circ}$?

Sexagesimal system
Circular system
Centesimal system
None of these
CorrectIncorrect
Correct answer is: Sexagesimal system
In the sexagesimal system, a complete angle is represented as $360^{\circ}$.
5

In radians, a complete angle is represented as _____.

$\pi$
$2\pi$
$3\pi$
$\frac{\pi}{2}$
CorrectIncorrect
Correct answer is: $2\pi$
In radians, a complete angle is represented as $2\pi$.

Frequently Asked Questions about Complete Angles

The six major types of angles, based on measurement, are right angle, straight angle, reflex angle, obtuse angle, acute angle, and complete or full rotation angle.

A complete angle is an angle that measures 360 degrees. A reflex angle, on the other hand, is an angle that is greater than 180 degrees but less than 360 degrees.

Engineers and architects use angles for measurement, designing roads, building, etc. Carpenters use it to make equipment like chairs, sofas, tables, etc. Artists use their measurement knowledge to sketch or create art pieces.

Degrees or radians are typically used to measure angles. Any unknown angle can be measured with a protractor or a measuring tool.

No, a $180^{\circ}$ angle is a straight angle. A $360^{\circ}$ angle makes a complete angle.

A 360 degree angle is called a complete angle.