1. BY: KAREEMA DOMINGO
STUDENT NUMBER: 200971653

2. WHAT IS A TRIANGLE?
Triangles are shapes with three straight sides.

3. * An EQUILATERAL TRIANGLE is a triangle
with all three sides of equal length. The
three angles are also all equal.
* An ISOSCELES TRIANGLE is a triangle
with two sides of equal length. The two
angles opposite the equal sides are also
equal to one another.
* A RIGHT-ANGLED TRIANGLE is a triangle
with one angle that is a right angle.

4. * A SCALENE TRIANGLE is a triangle with all
the sides of different lengths. The angles
are also all different.
* An ACUTE-ANGLED triangle is a triangle with
all the sides acute, i.e. less than 90°.
* An OBTUSE-ANGLED triangle is a triangle
with one obtuse angle, i.e. more than 90°.

5. It is a general convention that equal
sides are marked by drawing a short
line, /, through them , and a right
angle is marked by a square between
the arms of the angle . If sides
and angles are not marked, do not
assume that they are equal, just
because they look equal!

6. The interior angles of a triangle always add up
to 180°. Because of this, only one of the angles
can be 90° or more. In a right triangle, since
one angle is always 90°, the other two must
always add up to 90°.(i.e. V1 + V2 + V3 = 180°)
The sum of the two opposite angles in a triangle is
50° equal to the outside angle. Therefore, angles
a
a + b = d and, angle b = d (110°) – a (50°) = 60°.
As a result, c = 80°. Reason, the interior angles of a
triangle always adds up to 180°.
b c 110° d

7. a. What kind of triangle is shown in
each of the diagrams ?
Pare the options below with the
letter of the triangle:
b.
Acute
Obtuse
c. Right triangle
Scalene
Isosceles
d. Equilateral

8. The "Many Triangles" problem
In the figure below, the lines BC, AD and FT are parallel.

9. Problem 1
How many right triangles are there?
(If you are assuming the angle abk, and the three
others like it, is 90° you will need to prove it first).
Problem 2
How many isosceles triangles are there?
Problem 3
How many triangles altogether?

10. A. In the shape abcd, the angles
d
b = 30°and c = 75°. Calculate
a angles a and d. Give reasons
30°
for your answer.
b
75°
c
B. Identify the type of triangle
a
and calculate angle a.
35° 105°

11. a. Right triangle
b. Obtuse
c. Acute
d. Obtuse

12. Number of right triangles: 20
abj, afj, dcp, dtp, jbk, jfk, gmk, hmk, gmn, hmn,
cpn, tpn, bfh, gfh, gth, cth, fbg, hbg, hgc, tgc
Number of isosceles triangles: 14
abf, dct, bkf, gkh, gnh, cnt, bkg, fkh, gnc, hnt
bhc, fkt, kgn, khn
Total number of triangles : 38
abj, afj, bjk, fjk, gkm, hkm, gnm, hnm, cnp, tnp,
cpd, tpd, bkg, fkh, gnc, hnt, baf, cdt, abk, afk, dcn,
dtn, bkf, gkh, gnh, cnt, bfh, gfh, fbg, hbg, ght, cht,
hgc, tcg, fgt, bhc, gkn, hkn

13. A. Angle a = 75°
Angle d = 105°
B. Obtuse triangle
Angle a = 40°

16. AllKidsNetwork.com. (2006). AllKidsNetwork.com. Retrieved April 30, 2012, from allkidsnetwork.com/crafts/shapes/triangle-shape-monster.asp:
http://www.allkidsnetwork.com/crafts/shapes/triangle-shape-monster.asp
Battista, A. (2008). Irenebrination: Notes on Architecture, Art, Fashion and Style. Retrieved April 29, 2012, from Irenebrination: Notes on
Architecture, Art, Fashion and Style: http://www.irenebrination.typepad.com/irenebrination_notes_on_a/2010/07/impossible-cities-
wearable-triangular-architectures.html
Brachhold, A. (2011, October 19th). Types of Triangles. Retrieved April 30, 2012, from Types of Triangles: http://typesoftriangles.org/
Connection, R. (2003). Building Strong Shapes with Triangles. Retrieved April 29, 2012, from Roger's ConnectionTM Magnetic Construction Toy:
http://www.rogersconnection.com/triangles/
Godin, S., Casey, M., Brown, C., Hildebrand, G., Brown, J., Collegeman, A., et al. (2005). Educational Toys For Infants And Babies. Retrieved April 30th,
2012, from Squidoo: http://www.squidoo.com/educational-toys-for-infants-and-babies
Jauhari, N. (2010, July 31). Inehome. Retrieved April 29, 2012, from http://inehome.com/triangle-tables-white-minimalist-design-table/
Jurvetson, S. (2008, July 8th). OpenLearn LabSpace. Retrieved 04 29, 2012, from OpenLearn LabSpace:
http://labspace.open.ac.uk/mod/resource/view.php?id=420267
Miller, J. F. (2000, July). Custom Celtic Design Wedding Rings Page. Retrieved April 30th, 2012, from Tradeshop Incorporated:
http://www.tradeshop.com/master/custom2.html
Page, J. D. (2009). Math Open Reference. Retrieved 04 29, 2012, from The Math Open Reference Project:
http://www.mathopenref.com/tocs/anglestoc.html
Phillip, G. (2006, September 18th). Missed Contentions . Retrieved April 29th, 2012, from Missed Contentions :
http://blog.lib.umn.edu/phil0459/archtecture/