Page 139 - NUMINO TG_5A

Workbook The Beauty of Halves

154-B1-1 154-B1-2

Areas of Triangles (1)

1. Find the area of each triangle. 2. Find the area of each triangle ( 1 cm2 ).
Example
Example You can make a square with
two congruent triangles.
The area of the triangle is: The area of a triangle is half the
+++++ (+=) area of a square.
So, 16 2 8 cm2.
It is the same as: + + +

units

a. b. a. b.

units units cm2 cm2
c. d.
c. d.

units units
e. f.
cm2 cm2
e. f.

units units

Objective Find the area of triangles by cm2 cm2
counting squares.
Objective Find the area of triangles by
Textbook Reference Lead-In counting squares.

Textbook Reference Lead-In

154-B2-1 154-B2-2

Same Areas 2. Find the triangle with a different area ( 1 cm2 ).
1. Match each triangle to the rectangle that has the same area. Example

a.

b. A B CD

c. The base of all the triangles is 3 cm. The height of triangles A, B, and D is
5 cm and the height of triangle C is 4 cm. All of the triangles have the
same base length, but not height. Triangle C has a different height
compared to the others. So, triangle C is the triangle with a different area.

a.

d. A BC D

e. b.
A
BC D

Objective Match triangles and rectangles Objective Find triangles with the same area.
with the same area. Textbook Reference Activity 2

Textbook Reference Activity 2

122 NUMINO Teacher s Guide