Name: ________________________________ Hour: _____ Date: _______________________
U4 Geometry
Construct/draw geometric shapes with specific conditions
Construct triangles when given specific angle and length conditions
1.
Name the type of angle. Then use your protractor to measure each angle.
2.
Create <OMG that is 50 o
.
1

Constructing Triangles – two sides and an angle http://www.slideshare.net/adamharbott/constructing-an-angle-or-triangle-using-a-protractor
Example1)
Make a triangle with one side 7 cm long , one side 4 cm long, and an angle that measures 45° .
Step 1: Begin by using a ruler to draw a line that is equal to the longer side length given.
Step 2: Place center of protractor at one end of line. Be sure that the line of the protractor lines up with the line on your paper.
Step 3: Mark 45° at edge of protractor. ( Does your angle look acute?)
Step 4: Put 0cm mark on same end of first line and line up with 45° mark.
Step 5: Use a ruler to draw a 4cm line along the ruler. The line may not go all of the way to the mark that you made.
Step 6: Using the ruler, connect the end of the 4cm line with other end of the 7cm line to complete the triangle.
Step 7: Label the lines and angles that you were given measurements for from the problem: 4cm,
45°, 7cm
Practice:
As you have finish creating one triangle, swap with a partner to check their triangle.
1.
Make a triangle with one side of 5 cm, one side of 10 cm and there is an angle of 45 o
2.
Make a triangle with one side of 7 cm, one side of 8 cm and there is an angle of 30 o
3.
Make a triangle with one side of 9 cm, one side of 4 cm and there is an angle of 50 o
4.
Make a triangle with one side of 7 cm, one side of 2 cm and there is an angle of 80 o
2

Constructing Triangles - two angles and a side http://www.cimt.plymouth.ac.uk/projects/mepres/book7/bk7i5/bk7_5i5.htm
Example2)
Make a triangle with one angle that measures 50°, another angle that measures 30°, and one side length of 8cm .
Step 1: Begin by using a ruler to draw a base line that is equal to the side length given.
Step 2: Place center of protractor at one end of line. Be sure that the line of the protractor lines up with the line on your paper.
Step 3: Mark 50° at edge of protractor. ( Does your angle look acute?)
Step 4: Use a ruler to draw a line from the end of the base line to the 50° mark.
Step 5: On the opposite side of the base line, measure and mark 30°.
Step 6: Using the ruler, draw a line from the end of the base line to the 30° mark. It should overlap the 50° line.
Step 7: The intersection of the lines is the third vertex of the triangle. You can erase the top parts of your construction lines. ( As a check, the third angle should measure 100°.
)
Step 8: Label the lines and angles that you were given measurements for from the problem: 50°,
30°, 8cm
Practice:
As you have finish creating one triangle, swap with a partner to check their triangle.
1.
Make a triangle with one side of 7 cm, an angle of 60 o , and another angle of 25°
2.
Make a triangle with one side of 4 cm, an angle of 70 o
, and another angle of 70°
3.
Make a triangle with one side of 12 cm, an angle of 100 o
, and another angle of 40°
3

Constructing Triangles - three sides http://www.cimt.plymouth.ac.uk/projects/mepres/book7/bk7i5/bk7_5i5.htm
Example3)
Make a triangle ABC with side lengt hs of 7cm, 8cm , and 9cm .
Step 1: Begin by using a ruler to draw a base line that is equal to the longest side length given.
Label the left end point A and the right end point B.
Step 2: The point of the compas and the pencil should be 8 cm apart. Place the point of the compass on point A. Create an arc.
Step 3: Repeat the process from point B. The point of the compas and the pencil should be 7 cm apart. Place the point of the compass on point B. Create an arc.
Step 4: The Arcs should intersect. The intersection of the arc is the third vertex of the triangle.
Step 5: Then use a ruler to connect points of the triangle.
Step 6: You can erase the top parts of your construction lines
Step 7: . Label the lines measurements that were given for from the problem: 7cm, 8cm, 9cm
Practice:
As you have finish creating one triangle, swap with a partner to check their triangle.
1.
Make a triangle with side lengths that are: 7 cm, 4cm, and 8cm
2.
Make a triangle with side lengths that are: 15 cm, 12cm, and 8cm
3.
Make a triangle with side lengths that are: 3 cm, 3cm, and 4cm
4.
Make a triangle with side lengths that are: 6 cm, 6cm, and 6cm
4