Loading [MathJax]/jax/output/HTML-CSS/jax.js

Construction of Angles by using Compass

In construction of angles by using compass we will learn how to construct different angles with the help of ruler and compass.

There are some angles of special measures which can be constructed without use if protractor. Let us discuss a few here to learn how to construct them.


1. Construction of an Angle of 60° by using Compass

Step of Construction:

(i) Draw a ray OA.

(ii) With O as centre and any suitable radius draw an arc above OA cutting it at a point B.

(iii) With B as centre and the same radius as before, draw another arc to cut the previous arc at C.

(iv) Join OC and produce it to D.

Then ∠AOD = 60°.


Working Rules to Construct an Angle Measuring 60°.

Given: AB be the given line with point O.

To Construct: Draw a ray OC such that COB is 60°.

Step I: Draw a line AB and mark the point O an it.

Draw a Line AB


Step II: Draw an arc using O as centre cutting OB at M.

Step III: Now, use M as the centre and OM as radius, draw another are cutting the previous arc at N.

Draw an Arc using O as Centre


Step IV: Join O and N and produce it to form OC.

Construct an Angle Measuring 60°

Step V: Now, ∠COB is the required angle whose measure is 60°.


2. Construction of an Angle of 120° by using Compass

Step of Construction:

(i) Draw a ray OA.

(ii) With O as centre and any suitable radius draw an arc cutting OA at B.

(iii) With B as centre and the same radius cut the arc at C, then with C as centre and same radius cut the arc at D. Join OD and produce it to E.

Then, ∠AOE = 120°.


Working Rules to Construct an Angle Measuring 120°.

Step I: Draw a line AB and mark the point O on it.

Step II: Draw an arc using O as centre cutting OB at M.

Step III: Now, use M as the centre and ¯OM as radius, draw another arc cutting the previous arc at N.

Draw an Arc using O as Centre


Step IV:
Now, take N as the centre and keeping the radius same (¯OM), mark another arc cutting at T.

Angle Measuring 120°


Step V: Join ¯OT and produce it to form the ray OE.

Construct an Angle Measuring 120°

Step VI: Now, ∠EOB is the required angle measuring 120°.


3. Construction of an Angle of 30° by using Compass

Step of Construction:

(i) Construction an angle ∠AOD = 60° as shown.

(ii) Draw the bisector OE of ∠AOD.

Then, ∠AOD = 30°.


Working Rules to Construct an Angle Measuring 30°.

We have studied to construct an angle measuring 60°. Also, we have studied how to bisect an angle. Now, we would learn to draw an angle measuring 30° by first constructing an angle of 60° and then bisecting it.

Given: AB be the given line with point O.

Step I: Draw a line AB and mark the point O.

Step II: Draw an arc using O as centre cutting OB at M.

Step III: Now, use M as the centre and OM as radius, draw another arc cutting the previous arc at N.

Step IV: Join O and N and produce it to form OC.

Thus, ∠COB = 60° is formed.

Construct an Angle Measuring 60°


Step V:
Now, taking N and M as centres, draw two same arcs cutting each other at X.

Constructing an Angle


Step VI: Join OX as it is the bisector of angle ∠COB (which is 60°), and producing it to form ray OD.

Construct an Angle Measuring 30°

Step VII: Now, ∠DOB is the required angle measuring 30°.


4. Construction of an Angle of 90° by using Compass

Step of Construction:

(i) Take any ray OA.

(ii) With O as centre and any convenient radius, draw an arc cutting OA at B.

(iii) With B as centre and the same radius, draw an cutting the first arc at C.

(iv) With C as centre and the same radius, cut off an arc cutting again the first arc at D.

(v) With C and D as centre and radius of more than half of CD, draw two arcs cutting each other at E, join OE.

Then, ∠EOA = 90°.


Working Rules to Construct an Angle Measuring 90°.

Step I: Draw a line AB and mark the point O on it.

Step II: Draw an arc using O as centre cutting OB at M.

Draw an Arc using O as Centre


Step III:
Now, using M as the centre and OP as radius, draw another arc cutting the previous arc at N.

Step IV: Now, taking N as the centre and keeping the radius same (OM), mark another arc cutting at T.

Angle Measuring 120°


Step V: Now, using N and T as centres, draw two arcs of the same radius cutting each other at Y.

Angle Measuring 90°


Step VI: Join OY and produce it to form the ray OF.

Construct an Angle Measuring 120°

Step VII: Now, ∠FOB is the required angle measuring 90°.


5. Construction of an Angle of 75° by using Compass

Step of Construction:

(i) Take a ray OA.

(ii) With O as centre and any convenient radius, draw an arc cutting OA at C.

(iii) With C as centre and the same radius, draw an cutting the first arc at M.

(iv) With M as centre and the same radius, cut off an arc cutting again the first arc at L.

(v) With L and M as centre and radius of more than half of LM, draw two arcs cutting each other at B, join OB which is making 90°.

(vi) Now with N and M as centres again draw two arcs cutting each other at P.

(vii) Join OP

Then, ∠POA = 75°.


6. Construction of an Angle of 105° by using Compass

Step of Construction:

(i) After making 90° angle take L and N as centre and draw two arcs cutting each other at S.

(ii) Join SO.

Then, ∠SOA = 105°.


7. Construction of an Angle of 135° by using Compass

Step of Construction:

(i) Construct ∠AOD = 90°

(ii) Produce ∠AO to B.

(iii) Draw OE to bisect ∠DOB.

     ∠DOE = 45°

     ∠EOA = 45° + 90° = 135°

Then, ∠EOA = 135°.


8. Construction of an Angle of 150° by using Compass

Step of Construction:

(i) Construct ∠AOC = 120°

(ii) Produce ∠AO to B.

(iii) Draw OD to bisect ∠COB.

Now ∠COD = 30°

Therefore, ∠AOD = 120° + 30° = 150°

Then, ∠AOD = 150°.


9. Construction of an Angle of 45° by using Compass

Step I: Draw a line AB and mark the point O on it.

Step II: Draw an arc using O as centre cutting OB at M. Now, use M as the centre and OM as radius, draw another arc cutting the previous arc at N.

Step III: Now, take N as the centre and keeping the radius same (¯OM), mark another arc cutting at T. 

Step IV: Now, using N and T as centres of the same radius, draw two arcs cutting each other at Y.

Step V: Join ¯OY and produce it to form a ray OF, Thus, ∠FOB = 90° is formed.

Construct an Angle Measuring 120°

Step VI: Let OY cut the arc at U. Use U and M as centres, draw two arcs of the same radius cutting each other at Z.

Angle Measuring 45°


Step VII: Join ¯OZ and produce it to form a ray OG.

Construct an Angle Measuring 45°

Step VIII: Now, ∠GOB is the required angle measuring 45°.


Constructing a Copy of an Angle Using Compass and Straight-Edge:

Let us draw an angle whose measure is equal to that of the angle, say angle ABC.

Copy of an Angle

Step I: With the vertex B as centre and taking a suitable radius, draw an arc to cut the arms BA and BC of ABC at X and Y respectively.

Copy of an Angle Using Compass


Step II:
Draw a ray OQ.

Draw a Ray OQ


Step III:
With O as centre nd BX (or BY) as radius, draw an arc which intersects OQ at L.


Step IV:
With L as centre and XY as radius, draw another arc to cut the previous arc at M.

Constructing a Copy of an Angle


Step V: Join O and M, and OM is produced to form the ray OP. Now, ∠POQ is the required angle which is the copy of ∠ABC.

You might like these


● Angle.

Interior and Exterior of an Angle.

Measuring an Angle by a Protractor.

Types of Angles.

Pairs of Angles.

Bisecting an angle.

Construction of Angles by using Compass.

Worksheet on Angles.

Geometry Practice Test on angles.





5th Grade Geometry Page

5th Grade Math Problems

From Construction of Angles by using Compass to HOME PAGE




Didn't find what you were looking for? Or want to know more information about Math Only Math. Use this Google Search to find what you need.



New! Comments

Have your say about what you just read! Leave me a comment in the box below. Ask a Question or Answer a Question.




Share this page: What’s this?

Recent Articles

  1. Quadrilaterals | Four Sided Polygon | Closed Figure | Adjoining Figure

    Jul 14, 25 02:55 AM

    Square
    Quadrilaterals are known as four sided polygon.What is a quadrilateral? A closed figure made of our line segments is called a quadrilateral. For example:

    Read More

  2. Formation of Numbers | Smallest and Greatest Number| Number Formation

    Jul 14, 25 01:53 AM

    In formation of numbers we will learn the numbers having different numbers of digits. We know that: (i) Greatest number of one digit = 9,

    Read More

  3. 5th Grade Geometry Practice Test | Angle | Triangle | Circle |Free Ans

    Jul 14, 25 01:53 AM

    Name the Angles
    In 5th grade geometry practice test you will get different types of practice questions on lines, types of angle, triangles, properties of triangles, classification of triangles, construction of triang…

    Read More

  4. 5th Grade Circle Worksheet | Free Worksheet with Answer |Practice Math

    Jul 11, 25 02:14 PM

    Radii of the circRadii, Chords, Diameters, Semi-circles
    In 5th Grade Circle Worksheet you will get different types of questions on parts of a circle, relation between radius and diameter, interior of a circle, exterior of a circle and construction of circl…

    Read More

  5. Construction of a Circle | Working Rules | Step-by-step Explanation |

    Jul 09, 25 01:29 AM

    Parts of a Circle
    Construction of a Circle when the length of its Radius is given. Working Rules | Step I: Open the compass such that its pointer be put on initial point (i.e. O) of ruler / scale and the pencil-end be…

    Read More