How To Draw A Triangle Using A Protractor

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Loci and constructions

Loci are a set of points with the same property. Loci tin can be used to accurately construct lines and shapes. Bearings are three effigy angles measured clockwise from North.

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Constructing triangles

Triangles and other shapes tin exist accurately constructed using a protractor, a pair of compasses and a ruler.

In guild to draw a triangle, three properties are needed:

1. SAS - Side Angle Side
2. ASA - Angle Side Angle
3. SSS - Side Side Side

Constructing triangles given SAS

The lengths of two sides and the size of the angle in between are needed.

Example

Make an authentic drawing of a triangle with lengths 4 cm and half-dozen cm with an bending of twoscore° in betwixt.

Depict the longest side using a ruler

Utilise a protractor to measure the 40° angle. Put the centre of the protractor on the point A. Count from nothing degrees from the horizontal line to 40° and put a mark at this betoken. This is point B

Use a ruler to draw a line from A to B so information technology is iv cm long

Depict in the third side of the triangle from B to C

Constructing triangles given ASA

The sizes of two angles and the length of the side in between are needed.

Example

Make an authentic drawing of a triangle with the angles twoscore° and lxx°, with a side of length eight cm in between.

Depict the side using a ruler

Use a protractor to measure out the 40° angle. Put the centre of the protractor on bespeak D. Count from zero degrees from the horizontal line to 40°. Put a structure mark at twoscore°

Use a ruler to draw a line from D through the construction mark. Arrive long

Utilise a protractor to measure the 70° angle from E. Put the center of the protractor on bespeak Due east. Count from zero degrees from the horizontal line to 70°. Put a mark at 70°, bespeak F

Utilise a ruler to describe a line from E to F. Make sure it crosses the 40° line

Constructing triangles given SSS

The lengths of all iii sides are needed.

Example

Make an accurate drawing of a triangle with sides of length 3 cm, 5 cm and half dozen cm.

Describe the longest side using a ruler

Open up the pair of compasses until they are 5 cm wide. Use a ruler to measure it. Describe an arc from point H above the line

Open the pair of compasses until they are 3 cm wide. Use a ruler to measure it. Depict an arc from point J above the line

Join the arc to the points H and J using a ruler

As with all constructions, ensure that the structure lines are not rubbed out. These bear witness that the triangles were accurately constructed.

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Source: https://www.bbc.co.uk/bitesize/guides/zx2sb82/revision/4

Posted by: wellersualking.blogspot.com

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