The indigenous "complementary" come from two Latin words "Complere" and also "Plere". "Complere" way "complete", whereas "Plere" means "fill". For this reason "complementary" way "something the completes and also brings perfection." and also so space complementary angles, a pair of two angles that amount up to 90 degrees, forming a best angle.

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A part of bread is rectangular in shape, yet when the is separated into two pieces by cutting along the diagonal, two ideal triangles room formed, each through a pair of safety angles. In this lesson, we will check out the world of security angles.

1.What are Complementary Angles?
2.Adjacent and Non-Adjacent security Angles
3.How to find the match of an Angle?
4.Properties of security Angles
5.Complementary angles v/s Supplementary Angles
6.Complementary angle Theorem (with Illustration)
7.FAQs on safety Angles

What are Complementary Angles?

The complementary and also supplementary that the 2 angles is determined by the sum of their measurement. If the sum of the 2 angles is equal to the measure up of a appropriate angle then the pair of angle is said to be complementary angles.

Complementary angle Definition:

Two angle are stated to be complementary angle if they include up come 90 degrees. In other words, when complementary angles are put together, they type a ideal angle (90 degrees). Edge 1 and also angle 2 space complementary if the amount of both the angles is same to 90 levels (angle 1+ angle 2 = 90°) and also thus, angle 1 and also angle 2 are called complements of each other.

Complementary angle Example:

In the figure given below, 60° + 30° = 90°. Hence, from the "Definition of security Angles", these 2 angles are complementary. Each angle among the complementary angle is referred to as the "complement" that the various other angle. Here,

60° is the match of 30°30° is the enhance of 60°


Adjacent and Non-Adjacent safety Angles

If the sum of 2 angles is equal to the measure of a appropriate angle then the pair of angle is recognized as the safety angle. There room two species of complementary angle in geometry as offered below:

Adjacent complementary AnglesNon-adjacent safety Angles

Adjacent complementary Angles: 2 complementary angles through a typical vertex and also a common arm are referred to as adjacent complementary angles. In the number given below, ∠COB and also ∠AOB are nearby angles together they have actually a common vertex "O" and also a typical arm "OB". Lock also add up to 90 degrees, the is ∠COB + ∠AOB = 70°+20° = 90°. Thus, these 2 angles are nearby complementary angles.


Non-adjacent security Angles: 2 complementary angles that space NOT surrounding are stated to it is in non-adjacent safety angles. In the number given below, ∠ABC and also ∠PQR are non-adjacent angle as castle neither have actually a usual vertex no one a common arm. Also, they add up come 90 levels that is, ∠ABC + ∠PQR = 50° + 40° = 90°. Thus, these two angles space non-adjacent security angles. Once non-adjacent complementary angle are placed together, they type a right angle.


How come find complement of an Angle?

We know that the amount of two complementary angles is 90 degrees and also each of lock is said to be a "complement" of every other. Thus, the enhance of an edge is discovered by individually it from 90 degrees. The match of is 90-x°. Let's uncover the match of the angle 57°. The enhance of 57° is acquired by subtracting it indigenous 90°. 90° - 57° = 33°. Thus, the complement of 57° angle is 33°.

Properties of security Angles

Now us have currently learned around the types of complementary angles. Let's have actually a look at some essential properties of complementary angles. The nature of complementary angles are offered below.

Two angle are stated to it is in complementary if they add up to 90 degrees.Two safety angles deserve to be either surrounding or non-adjacent.Three or an ext angles cannot be complementary also if their sum is 90 degrees.If two angles are complementary, each angle is dubbed "complement" or "complement angle" that the other angle.Two acute angles of a right-angled triangle room complementary.

Complementary angles v/s Supplementary Angles

The supplementary and complementary angles are angles the exist in pairs, summing up to 180 and also 90 degrees, and also have plenty of real-time applications, most typical being the crossroads. Let's have actually a look in ~ the difference in between them.

The supplementary vs complementary angle table:

Supplementary AnglesComplementary Angles
A pair of edge are claimed to be supplementary if their amount is 180 degrees.A pair of angle are claimed to be complementary if their amount is 90 degrees.
Supplement that an edge x° is (180 - x)°The enhance of an edge x° is (90 - x)°

Here is a brief trick because that you to recognize the difference in between supplementary angles and also complementary angles.

"S" is because that "Supplementary" and "S" is because that "Straight." Hence, you can remember that 2 "Supplementary" angles when put together form a "Straight" angle."C" is for "Complementary" and also "C" is for "Corner." Hence, you can remember that two "Complementary" angles once put together type a "Corner (right)" angle.

Complementary angle Theorem (with Illustration)

If the amount of two angles is 90 degrees, then us say that they space complementary. Every of the complement angles is acute and also positive. Let's examine the complementary edge theorem v its proof. The complementary edge theorem states, "If two angles are complementary come the very same angle, then they space congruent to each other".

Proof of Complementary angle Theorem

We understand that complementary angle exist in pairs and sum upto 90 degrees. Think about the following figure and prove the complementary angle theorem.


Let us assume the ∠POQ is complementary to ∠AOP and also ∠BOQ.Now together per the definition of complementary angles, ∠POQ + ∠AOP = 90° and also ∠POQ + ∠BOQ =90° .From the over two equations, we have the right to say that "∠POQ + ∠AOP = ∠POQ + ∠BOQ".Now subtract '∠POQ' indigenous both sides, ∠AOP = ∠BOQHence, the to organize is proved.

☛Related Articles

Check out the adhering to important write-ups to know much more about complementary angles.

Example 1:

Find the edge x in the complying with figure.



In the given figure, x and 62° space complementary together they form a ideal angle. Hence, their sum is 90°

x + 62° = 90°

x = 90° - 62°

x = 28°

Therefore, the angle 'x' is 28°.

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Example 3: discover the value of x if the complying with two angles are complementary.



Since the given two angles space complementary, their sum is 90°. This means x/2 + x/3 = 90°, 5x/6 = 90°, x = 90° × 6/5 = 108°

Therefore, the worth of x is 108°

Example 4: 2 angles room complementary. The measure up of the larger angle is 5 degrees an ext than 4 time the measure of the smaller sized angle. What is the measure of the larger angle in degrees?


Let us assume the the 2 complementary angles are x (larger) and also y (smaller). By the given information, x = 4y + 5. Due to the fact that the two angles room complementary, their sum is 90°, x + y = 90°⇒ (4y + 5) + y = 90°⇒ x = 4y + 5⇒ 5y + 5 = 90°, 5y = 85°, y = 17°