__maths__>__Construction / Practical Geometry (basics)__>__4 Fundamentals Elements of Practical Geometry__### Geometrical Instruments

In this page, overview of the geometrical instruments is provided

• graduated ruler or scale

• compass

• protractor

• divider

• set-squares or set-triangles

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What is the geometrical instrument in the figure called?

- ruler
- ruler
- compass
- divider
- protractor

The answer is "ruler"

What is a "ruler" used for?

- to construct an arc
- to construct a straight line
- to construct a straight line

The answer is "to construct a straight line"

What are the marks on the ruler?

- the length measure, millimeter and centimeter, is marked
- the length measure, millimeter and centimeter, is marked
- no markings are found in a ruler

The answer is "the length measure is marked"

Other than to construct straight lines, what is a "ruler" used for?

- to measure an angle
- to measure a line-segment
- to measure a line-segment

The answer is "to measure a line-segment"

Which of the following is a meaning for the word "ruler"?

- a straight stick
- a straight stick
- a book of rules

The answer is "a straight stick". The word "ruler" is derived from a root word meaning straight stick.

What is the term used to refer "a straight stick"?

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The answer is "ruler".

Which of the following is a meaning for the phrase "graduated ruler"?

- a straight stick with grade of length measure marked on it
- a straight stick with grade of length measure marked on it
- a book of rules for graduates

The answer is "a straight stick with grade of length measure marked on them".

Note: A ruler is also referred with the name "scale".

**Graduated Ruler or scale** : A ruler is a straight stick with grade of length measure marked. It is used to construct straight lines and measure a line-segment.

What is the geometrical instrument in the figure called?

- compass
- compass
- protractor

The answer is "compass"

What is a "compass" used for?

- to construct an arc of given radius
- to construct an arc of given radius
- to construct an angle of given measure

The answer is "to construct an arc of given radius". The arc has points that are in equal distance from the center point.

The word "compass" is (possibly) from root words "com+pace" meaning "together+take-steps".

What is the term used to refer "the instrument to mark an arc"?

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The answer is "compass".

**Compass** : An instrument to measure a length and construct an arc of a given radius.

What is the geometrical instrument in the figure called?

- compass
- divider
- divider

The answer is "divider".

What is a "divider" used for?

- to measure the length between two points
- to measure the length between two points
- to mark an angle

The answer is "to measure the length between two points"

What is the term used to refer "the instrument used to measure length between points"?

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The answer is "divider".

**Divider** : is a geometrical instrument which is used to measure the length between two points.

What is the geometrical instrument in the figure called?

- squares
- protractor
- protractor

The answer is "protractor".

What is "protractor" used for?

- to mark length of a line segment
- to mark an angle of given measure
- to mark an angle of given measure

The answer is "to mark an angle of given measure"

The word "Protractor" is from root words "protract+tor", which means "draw-out or lengthen a line".

What is the term used to refer "instrument to mark an angle of given measure"?

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The answer is "protractor".

**Protractor** : is a geometrical instrument which is used to mark a measure of an angle.

What is the geometrical instrument in the figure called?

- set squares
- set triangles
- either one of the above
- either one of the above

The answer is "either one of the above". The name "set squares" calls by the two `90^@` angles provided by the instruments. The name "set triangles" calls by the shape of the two pieces. Both names are used.

What is "set squares" used for?

- to construct perpendicular and parallel lines
- to measure standard angles `90^@`, `30^@`, `45^@`, `60^@` etc.
- both the above
- both the above

The answer is "both the above"

What is the term used to refer "set of triangles with standard angles "?

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The answer is "set squares or set triangles".

**Set Squares or Set Triangles** : is a pair of triangular pieces used to construct parallel lines or to measure the standard angles `90^@`, `30^@`, `45^@`, `60^@` etc.

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