~ Module 8 Lesson 2* Notes ~
Classifying Triangles
TLW classify triangles by their angle measures and side
lengths
TLW use triangle classifications to find angle measures
and side lengths
Triangle Classification – by Angle Measures
Acute Triangle
Equiangular Triangle
Right Triangle
Obtuse Triangle
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TRY THIS!
CLASSIFY EACH TRIANGLE BY ANGLE MEASURES.
(a)
(b)
(c)
Triangle Classification – by Side Lengths
Equilateral Triangle
Isosceles Triangle
Scalene Triangle
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TRIANGLE – ON VACATION
CLASSIFY THE TRIANGLES BY SIDES.
(a)
(b)
(c)
DRAW AN EXAMPLE OF EACH TYPE OF TRIANGLE OR EXPLAIN WHY IF IT IS NOT POSSIBLE.
(a) isosceles right
(b) equiangular obtuse
(c) scalene right
(d) equilateral acute
(e) scalene equiangular
(f) isosceles acute
Find the side lengths of the triangles below.
(a)
(b)
y  ______
BC = ______
AC = ______
AB = ______
y  ______
BC = ______
AC = ______
AB = ______
THE TRIANGLE INEQUALITY THEOREM
THE SUM OF THE LENGTHS OF ANY TWO SIDES
OF A TRIANGLE IS GREATER THAN THE LENGTH
OF THE THIRD SIDE.
Decide which of the following sets of side lengths actually form a triangle.
(a) 1 cm, 2 cm, 5 cm
(d) 5 ft, 7 ft, 12 ft
(b) 4 cm, 2 cm, 5 cm
(e) 6 yds, 8 yds, 10 yds
(c) 3 cm, 2 cm, 5 cm
(f) 2 ft, 2 ft, 2 ft
Guided Practice
Classify each triangle by sides or angles.
1.
2.
3.
4.
Find the side lengths of the triangles below.
5.
6.
y  ______
BC = ______
y  ______
BC = ______
AC = ______
AB = ______
AC = ______
AB = ______
The lengths of two sides of a triangle are given. Find the range of possible lengths for the third side.
7. 4 yd., 19 yd.
8. 28 km, 23 km.
9. 9.2 cm, 3.8 cm
10. The lengths of two sides of a triangle are 3 feet and 5 feet. Which could be the length of the third side?
(a) 3 feet
(b) 8 feet
(c) 15 feet
(d) 2 feet